I love awkward, nerdy, quiet guys. Preferably with glasses. I prefer thin build over big muscles and don't find the gym-bunny look attractive at all. If you look like you spent the last 24 hours studying rather than pumping iron then I'm definitely interested! I think someone described it perfectly a few pages back - the naive, geeky, probably-a-virgin look. I'm also one of the minority women who prefers men to actually have emotions. I find human psychology absolutely fascinating, so if you have no feelings whatsoever (or pretend not to) then I'll grow bored very quickly. I can't read between the lines and miss a lot of subtlety, so obvious emotion is far easier for me to understand in another person. Unfortunately, society encourages men to behave like shallow, uber-macho fighting machines a lot of the time and I'm completely turned off people like that.
Also someone who shares my love of science, computers, gadgets and learning and who has a big brain. I think intelligence and the ability to think logically is an instant magnet. I have a preference for dark hair, but it's not a deal breaker.