I've played for one (a few years ago), because there were two simultaneous services at my parish and the deacon had recently died, so no clergyman was available for the second. Whether it should exist, I don't know, but I certainly don't prefer it.

Just a Liturgy of the Word/ashes service (not a Communion service) with readings in which the presider (a laywoman who herself has since gone home to God) offered a "reflection." I would guess that since you can have a Communion service with a layperson (though it's certainly not preferable), this was technically allowable.

And I should note that a year or two later, we got a new deacon, so it's not an issue now.

Ash Wednesday service conducted by no one?

I once entered a very prominent Catholic church in Houston on ash Wednesday at which there apparently was no ritual of any sort - only a small table set before the sanctuary on which was a dish of ashes and a note to the effect that one may say a prayer and apply the ashes to one's self.