Tie between Theodore Francis Leo and Doug Martsch. "Umm... who?" Frontmen of, respectively, 'Ted Leo and the Pharmacists' and 'Built to Spill'. Yes, I know Doug Martsch is also in The Halo Benders, The Tree People, The Suffocation Keep and performs solo. I prefer his BtS work.
Slightly less serious answer: the guy from Tokio Hotel. Sure, their music's terrible, but I totally wanna fu... umm, fornicate with him. I happen to think emo guys are really cute.