I love trading card games. I got into Magic for a while with some friends a long time ago, and just recently picked it up again. I had a friend once describe it to me as "a more portable Dungeons & Dragons" being that you can take cards anywhere pretty easily, although his description isn't quite right. I always loved the expandability offered in trading card games, it's fun to trade cards. Booster packs can be expensive though.
If anyone is unfamiliar with Magic or looking to get back in, they have a series of YouTube videos that will introduce you to the game and teach you how to play:
Part One:
http://www.youtube.com/watch?v=GadqHggATe8
Part Two:
http://www.youtube.com/watch?v=mCGJ_UUtS1Q
Part Three:
http://www.youtube.com/watch?v=Jik47gv8dn4
Part Four:
http://www.youtube.com/watch?v=qoO0fFAVXzE
Part Five:
http://www.youtube.com/watch?v=fG3eXBccyWg
Part Six:
http://www.youtube.com/watch?v=5FTAbftngf0