Edward Cullen (obv.)
Any HP character... but more specifically, Dean, Seamus, Oliver, Harry, Ron, Fred, George... etc...
Has anyone said Jack Sparrow from PotC yet? Yes, he's a drunken lunatic, but my God, is he a hot drunken lunatic.
The Doctor :)
Jem, once he's older, from To Kill A Mockingbird.
Akkarin, from the black magician trilogy
Ok, pretty much every book I've ever read contains someone I want to marry.
I am a terrible masochist, but I've always identified with him more than probably any other character I've encountered, so I would doom myself to a truly miserable marriage if it meant being married to Sydney Carton from A Tale of Two Cities.