Jonathan Coulton's First of May - NSFW
http://www.youtube.c.../u/28/gEjRHFom1Kk

He's done a number of songs in ASL, including Still Alive from Portal (this one's SFW)
http://www.youtube.c.../u/33/R9iXOtxu5Ro


found via today's Girls with Slingshots
http://www.daniellecorsetto.com/gws.html