ok so the title of this post sooo pulled me in, I screamed in my head "OMG SHELDON COOPER!!"
Yes, I am fully in love with Sheldon Cooper.
Michael Shanks (Daniel Jackson in Stargate SG-1, pre-haircut)
Seconding (thirding?) Jodie Foster's character in Contact.
He plays Jack Kelso in the video game L.A. Noire. Even his animated character is hot. :-P
Edited to add: Gil is probably the me-being-a-geek crush. I'd probably go Brian May or Tory Belleci from Mythbusters for geeky people I crush on.