Intelligence is sexy beyond belief. Attractive in the extreme. I wouldn't say my loved one is any kind of bishounen, but he's so smart (in addition to all those other good qualities, of course). I found myself reacting to watching him lecture once the way other women react to Robert Redford taking off his shirt. My academia fetish may be a little stronger than most, but the fact remains that an intelligent guy is exceedingly attractive to most geek girls.

It can't be dumb knowledge, though. An in-depth knowledge of Linux is probably not going to be a broad-spectrum aphrodisiac. A range of intelligence and a rudimentary personality are also important. I know one of the first things that truly impressed me about my boyfriend was that in addition to being a brilliant triple major in Physics-Math-Computer Science, he'd read Romance of the Three Kingdoms. The whole thing. More than once. Heart eyes! And he was impressed that in addition to my humanities specialties, I could discuss quantum theory and astrophysics (up to a certain point, anyway ;p).

Intelligence IS sexy. Rowr!