I play guitar and drums. I can sing when playing guitar, but god help me if I try to sing and play drums, lol. Timing goes straight to crap. There's been quite a few drummers who sang/ sing though...
Roger Taylor - Queen (sang the song "I'm in Love with my Car" and backup vocals)
Keith Moon - The Who (backup, sang lead on a few songs from "Quadrophenia" I think)
Phil Collins - Genesis
Dave Grohl - Foo Fighters, drummer on their first album wasn't he? Edit: And Nirvana of course, but I don't think he sang ever
Ringo Starr - Beatles (backup, and lead on "Yellow Submarine")
Kenny Jones - Small Faces
Peter Criss - Kiss
Karen Carpenter - The Carpenters
Phil Selway - Radiohead (backup/ harmony)
Don Henley - The Eagles
Dave Clark - Dave Clark 5
Mike Diamond - Beastie Boys, if that counts anyway
Meg White - White Stripes (I think she's a terrible drummer though... I equate her to Meg from Family Guy lol)
I'm in the process of forming a new band. From my last band, Piso Mojado, we've got me obviously (drums), Colin (bass), and Phil (guitar), and we're trying to find a vocalist. We might get my friend to sing, and her boyfriend plays sax, so that's a bonus. We can't find anywhere decent to set up and play though, I hate "studios" for rehearsing where you have twenty bands down the hall from you who play crappy Black Sabbath covers all day.