Veronica Mars: Possibly the only thing on this list that doesn't include some sort of fantasy element, or an extended universe. I've been with it since the beginning and I'm not abandoning it when it jumps to The CW this fall. The connections people make between Buffy annoy me since I hate the Buffy/Angel-verse, but I can live with it.
DCAU: Beautiful animation, awesome voice-work, and great continuity. They've aslo pushed the envelope many times during the many shows, which has become quite rare these days.
Wrestling: I got into it in 2000, lost interest in 2002, then got back into it in 2003. It's been pretty hard to get used to sporadic appearances of Stone Cold and The Rock, and the death of Eddie Guererro made me realized how much he was one of the reasons I got into it in the first place.
Nintendo: Specifically, Mario (duh), Pokemon, Fire Emblem, Advance Wars and Pikmin. I like pretty much any Nintendo franchise but the ones I listed I feel most close to.
Power Rangers: So I got into the show late, when it was losing popularity, but to this day I've been watching religously since mid-Turbo and I don't regret it. Well, maybe I do regret making my mom waste lots of money on the many toys and megazords but I still have most of them in top condition today, and they may save me from financial problems in the future.
Family Guy: I had loose interest in this show back when it had early life on Fox a few years back. It wasn't until I watched the first season in 2003 with my cousin during Christmas and even then I still didn't have cable which made it very hard to watch. I was so happy when I heard it had been resurrected by Fox and I have never missed an episode since it's return.
The glory days of Cartoon Network: I fondly remember watching Cartoon Cartoon Fridays without live action hosts and lame puppets. I also remember Toon Heads and Weekday Toonami, and Cartoon Theatre on Saturdays. Too bad at this point there's just no way they can ever go back to what they once were.