Magic The Gathering: It create the freakin' genre back in '93 and has been around since. It's a good game but alotta stuff has happened in the last few years, you may never fully catch up unless you jump into the deep end.
World of Warcraft: The TCG is flippin' amazing! It came out around a month ago so it's still very early... Not to mention that it's fun to play... No matter how many ulcers I get.
Naruto: It was good, but I never really got into it... A couple friends and I played and that was pretty much it. It was interesting nevertheless.
Dragonball Z/GT: My favorite card game to date... The original run of the Dragonball Z CCG to the Dragonball GT TCG was amazing and really got me into card games. I have yet to find a game that was a great as it was and I really doubt I will. Unfortunately, the final event was held at GenCon SoCal... So the game's officially dead.
There's tons of games out there... Just gotta look for 'em.