John Stanley's voluntaries are quite versatile for preludes or postludes or processionals. Especially the ones (which means most of them) which have 'trumpet tune' sections. The voluntaries of Wllm Boyce are equally fine, as are those of some others of that period.

Other similar literature would work as well.

Jonathan's mention of the 'Little Preludes and Fugues' by 'Bach' is good advice.

Look into the works of Couperin, de Grigny, LeBegue, Balbastre, and other Frenchmen of the baroque era. Numerous 'movements' from their organ masses and magnificats would be quite nice for your purposes.

Langlais' 'Organ Book' contains ten pieces of moderate difficulty, some of which might be useful to you. Ditto his Huit pieces modales.

There are a plethora of canzonas from the late renaissance or early baroque era which would make good ludes. Frescobaldi would be a prime 'suspect', but there are many others.

Search the organ chorale repertory. Many of these make very fine ludes. Bach's Orgelbuchlein would be a good place to start - but don't stop there.

The mid-twentieth century German, Hermann Schroeder wrote quite a number of short, easy to moderately difficult pieces that would be ideal for just such purposes as yours. Most of them should be well within your capabilities. Some are very festive.

Look into Oxford's 'manuals only' collections. Theses would offer much that you might delight in. Other publishers offer similar collections.

There are movements here and there from Tournemire's L'orgue mystique that are not difficult and may be suitable.

_________________________________________

Incidentally -
Prelude, Postlude.
We use these words all the time on the western edge of the pond, where they are preferred to the less prosaic 'voluntary'. Each refers to, one might say, 'something that is played', namely, played before or played after. -Lude derives from the Latin ludus, which means 'play', and which comes into English as the adjective 'ludic', meaning playful. Hence, pre-lude, or post-lude, or (tee-hee) perhaps a mid-lude - which would be a voluntary played at the offertory.

Johannes Peyer, a near contemporary of Bach. Two volumes I have of his stuff, manuals only.

I have lately been doing some research on Italian 16th-century organ repertoire and came across some things that might be a good start for you.

Girolamo Cavazzoni
-the best place to start is with his three organ Masses
-then try ricercari, canzoni, magnificats, hymns

Not a postlude, but this pastorale by Frescobaldi makes a lovely prelude. [edit: use the second edition listed, which is more recent and easier to read]

Giovanni Battista Fasolo
-a boatload of liturgically practical works; on the simpler side would be the three organ Masses. Some of the hymns, ricercari, & fugues would make good postludes. Almost everything you see on his IMSLP composer page are organ works.


I'm sorry I can't offer German suggestions at the moment. I'll be moving on to that within the next few weeks so if you stick around I might be able to give you something.

I second MJO. Pachelbel has some great chorale preludes as well as Magnificats for solo organ and they make great prelude/postlude material.

You ask about other Bach -
without giving a long list right now, it does occur to me that you might really enjoy his pastorale (BWV 590). Actually, this would seem more preludish or offertory or communionish than postludish, but it is a nice piece that you should get much use from. It has four distinct sections (movements, actually) which could be used independently. Strictly speaking, the pastorale is Christmas music, but I don't think that one needs to feel bound by that: emotionally, there are numerous times when it could be fitting. The first section has a pedal point whilst the rest are manualiter.
A pretty easy (and relatively short!) prelude and fugue that comes to mind is the e-minor (BWV 533) sometimes dubbed (who knows why!) 'the cathedral'. There are others which are relatively medium in difficulty.

It might be helpful from here on if you shared with us the details of your organ -
number of manuals, specifications, anything else of interest... age, builder, location.
You did say that it was 'nice', and you did refer to 'our little church', so, is it safe to assume that your organ is not too big?

Another really easy piece that you would enjoy would be Sweelinck's echo fantasia. This has a very easy left hand chordal support with right hand having continuous melody going from a louder to a softer sound in echo fashion. This would make a nice prelude, offertory, or communion on some occasions, but wouldn't really be postlude fare.

Now to the Orgelbuchlein -
these are some of the easiest pieces:

No.:
5. Puer natus in Bethlehem
9. Vom Himmel kam der Engel Schaar (this has running semi-quavers throughout but is best taken at a relatively moderate tempo. You might have fun learning this.
12. Jesu, meine Freude - probably somewhat challenging for you but not too difficult.
19. Herr Gott, nun schleuss den Himmel auf - doesn't go very fast, so don't be frightened of the continuum of semi-quavers. You may have fun with the relentless but not terribly difficult pedal part.
20. O Lamm Gottes, unschuldig - taken at a very modest tempo, rhythmically interesting, and exhibits canon betwixt bass and alto
21. Christe, du Lamm Gottes - this one is brief and definitely easy. Not too fast.
27. Christ lag in Todesbanden - a staple for organ students, not easy, but not too difficult if you really wish to tackle it.
28. Jesus Christus, unser Heiland - not difficult, some coordination challenges
40. Ich ruf' zu dir, Herr Jesu Christ - some coordination challenges with a continuous obbligato in the alto against steady quavers in the pedal. You may enjoy tackling this staple of organ students.
42. Wenn wir in Hochsten Nothen Sein - if you feel up to the intricacies of an highly ornamented melody against a not too challenging 'accompaniment' you might enjoy learning this lovely but rhythmically challenging piece - really nice for funerals and some Lenten days.

There you have it. Some of my colleagues may wonder why I put some of these on your list, or why I didn't put others on it. Not knowing exactly what you are capable of I opted to give you ample credit. Considering your obvious desire to grow you might give serious consideration to taking lessons from a nearby university-recommended organist. An Episcopalian would be the most likely help-mate in this regard.

Of course, your original question referenced postludes. Some of these would be appropriate as such, whilst others would be more fitting as preludes, offertories, or communions. Some also work well (get the Riemenschneider edition and check the chorale texts!) as wedding or funeral voluntaries.

8 Trumpet
4 Clarion (Is this another trumpet?)

Yes those are trumpets an octave higher than the 8.

To supplement Mr. Osborn's Bach suggestions:

Bach's Clavier-Übung III (sometimes referred to as the 'German Organ Mass') contains some of Bach's most challenging chorale preludes, but scattered throughout are settings of the same chorales for manuals-only. These are not too difficult and several make excellent postludes. While you are making your way through the Orgelbüchlein (which, charmingly, means 'little organ book'), you might want to take a look at these:

BWV 674 Kyrie, Gott heiliger Geist
BWV 677 Fughetta super: Allien gott in der Höh' sei Ehr'
BWV 679 Fughetta super: Diess sind die heil'gen zehn Gebot'
BWV 685 Christ, unser Herr, zum Jordan kam
BWV 689 Fuga super: Jesus Christ, unser heiland

The four 'Duetto's which follow the chorale preludes are also charming (written, I believe, to be played during Communion); Duetto III is my favorite, but Duetto IV (BWV 805) is one that could be played as a postlude with a bigger registration. Manuals-only pieces are totally legitimate!

Looks like you have a nice little organ to play! 'Ranks' refer to the individual sets of pipes that make up the organ. Each 'stop' on the organ activates a particular set of pipes, or rank. Mixtures are made up of multiple ranks—your swell mixture probably is made up of two ranks, and the Great mixture probably three. What this means for your organ, which has 21 'stops' but only 17 ranks, is that multiple 'stops' on the organ activate the same ranks—so, for instance, the Swell Clarion may well be the Trumpet rank at 4' (an octave higher—reed ranks being expensive), and the pedal 16', 8', and 4' stops probably draw on the same rank at different octaves. It's fun to figure out—go stop by stop, and compare, for instance, a note on the trumpet with the same note an octave lower on the Clarion.

Good luck with your Bach! And, as mentioned above, don't neglect Pachelbel.

Are there particular...

Actually, they are all pretty similar in structure and difficulty.
They typically consist of running parallel sixths and thirds and such, all in semi-quavers.
It can be challenging keeping track of changing directions (upward or downward) and of when the rapid parallel motion involves a change of interval.
Don't be frightened, though, these are wonderful pieces, not too lengthy, and should be very impressive on your little organ.
Just choose several that appeal to you and make friends with them.
I'm rather fond of the one in e-minor.

Also, the tempos can vary.
They may go 'like the wind', or may be taken at a tempo that suits your ability - all depending on how fast your fingers can go, and how fast you can think!
(The really important thing is 'flow', a continuum of line.)
Too, some of them present opportunities to change manuals - though you want to be careful that doing so compliments rather than savages the architectural integrity of the piece.

Roger - I would beware the Orgelbuchlein. It is often a go-to because of the shortness of the settings, but short does not necessarily mean "easy". Page-for-page, the orgelbuchlein settings are often Bach at his most contrapuntally dense and complex. And unlike a fugue or choral motet, all voices play all the time. That translates to constant coordination challenges, and a great deal of learning time to master a very short piece.

I give high marks to Mark's observations just above (and think much of his paedagogical thrust).

Having done so I will also agree fully with Jared that the Orgelbuchlein offers some of the great Sebastian's most challenging and 'contrapuntally dense' organ chorales.

There are pedaliter settings in the Clavier-Ubung, 'the Eighteen', the Schubler, and others that are less difficult and offer fewer technical challenges than quite a few items in the Orgelbuchlein.

'Little Book' that it is, it isn't, but for some few pieces, easy for average XXIst century beginners - maybe XVIIIth century ones, who literally ate, drank, and breathed that musical culture. The really good ones could even improvise that likes of what it takes many today months to learn. Such was their musical world.