You're spoiled for choice here, honestly.
Even if there's nothing in the Spare Character Concepts thread, there are oodles of playable PCs in the play-by-post section. Just look for threads that say Character Creation.
And if you're willing to dig, there are playable characters all over the place. My Character Request Game thread has some, the generic NPC thread has some, the various campaign settings in the campaign setting thread have some, and so on.
I believe there is also a one shot adventure where the players have to try and catch/stop pixies from sabatoging a pizza place. Finding the pixies is the hard part, I would imagine.
It's
here. Unfortunately it lacks pregens.