I'm 19, and in the process of joining the Marine Corps. And I'm into plenty of "nerdy" things.
Warhammer 40k, Magic the Gathering, Xbox 360, and of course tons of Halo.
"In Italy, for thirty years under the Borgias, they had warfare, terror, murder and bloodshed, but they produced Michelangelo, Leonardo da Vinci, and the Renaissance. In Switzerland they had brotherly love, they had five hundred years of democracy and peace, what did they produce? The cuckoo clock." - Orson Welles