I've mentioned before, I have the full EV Nova card game though few to play it with, and I used to play Yu-gi-oh though matt whomped me and noone to play it with anymore either. I recently picked up a starter pack on the Stargate Online TCG. The interface is solid, and there are available people to play against. The game is unique in the TCG world, whereas there are several methods of winning, and the focus is on exploration and winning missions not combat. You can perform a variety of actions on your villain turns, and a variety of events on your hero turns. I've been going by Rakden on it, if you get bored drop a 10 spot and stop on. Cheaper than online poker, and twice as fun. Seems there are tournaments and what not as well but I fear I'm too terrible to compete in one anytime soon, they do look like fun for those who like that competitive thang. They cost "event" tokens which are a buck a pop, Tournys range in cost from 1-25 token/tickets as far as I can tell the rewards falling in line with that. Even the smaller ones have decent rewards, get from one to several packs of cards plus special foil cards. Another neat thing is if you collect a full set you can redeem them for a free set of physical cards to play "offline".
Also check out the Nerd Handbook, It's a good read to understanding the geek/nerd mentality.