Magic: The Gathering - Yes, it's nerdy as hell... but damn is it fun, and it requires an amazing amount of logic, brainpower, and skill.
Check out the "Mana, I need that ring!" from Paul Michael Design. With rings corresponding to the 5 colors of Mana from Magic the Gathering, you'll be able to represent your favorite playstyle in style!
Magic: the Gathering Colored Drinking Glasses, $15 each!