Daru from Steins;Gate!!!!
He is fat, wears glasses, an adult, plays card games, hacks into CERN, and builds a time machine.
Lyod from Code Geass
He is more of a scientists guy then a nerd guy but still cool.
Haru from Accel World
He is as dorky looking as you can get however the computers there are all Augmented Reality based so there are no scenes of him on a physical computer but there will be scenes of him working on a heads up display from both his perspective (can see all the buttons and stuff he is pressing) and 3rd person perspective (just see him twiddling his fingers in mid-air) however he is a kid.
Zanz Bonus Points Tally
8bit_samurai: 1, CodeZTM: 1, Eake4: 2, ibabrak: 5, Mirkosp: 4, tipsd9video: 1, uncreative: 1