I think everyone has those TV shows that they've seen every single episode of countless times. When I was younger, I constantly had Nickelodeon or Disney on, and I'm sure I saw every episode of all of their shows a million times. The shows that I watch over and over have changed a little over the years (I haven't watched one of my Barney tapes in quite a long time), but there are a lot of shows that I've grown up watching, and I still watch all of the time.
Friends. My parents always watched Friends when it first aired, so I grew up watching it. I had to watch it every single week, and I now own almost all of the seasons on DVD (my sister owns the ones I don't). My whole family loves the show. In fact, my brother and sister watch it even more often than I do. Ji's currently borrowing half of the seasons, so we can't watch any of the later seasons at the moment. It's worth it though because Ji hadn't seen Friends much before, and it's nice that she can watch all of the awesomeness. I've heard every joke in every episode a million time, and I still find them insanely funny each time I watch them.
Avatar: The Last Airbender. Avatar, of course, is my favorite TV show of all time. I've been watching it since the first episode aired back when I was eleven. (I remember watching the first two episodes for the first time and laughing at all of the jokes...) I gathered all of the DVDs as they came out, and I rewatch the series all of the time. I have several things I do when I feel sad: read Harry Potter, watch Friends, or watch Avatar. Those are the things that never fail to make me happy. Avatar's a great show, and the episodes never get old.
Little House on the Prairie. Even though I've been reading the books since I was ten or so, it took me a bit longer to get into the TV series. I think I started watching it a year or two after reading the books. I rented some of the episodes, and then I started watching it on TVLand until they stopped showing re-runs, which made me really upset. I also watched them on Hallmark for a while, but I think they quit showing them too I'm in the process of collecting the DVDs, but there are some episodes I haven't seen in quite a long time, since I can't find a TV station that shows them anymore. (It's been a while since I checked. Maybe I should look for them again.) I've been watching the seasons that I do have on DVD though. I just love how happy this show is. Even during the sad times there's a happiness there. It's a somewhat cheesy show, but I love it. (Although I do enjoy the books even more, and for anyone who doesn't know, the books and TV show aren't really alike at all.)
Rugrats. This was one of the Nickelodeon shows that I watched over and over on TV as a kid, but I (or my family rather) also own tons of Rugrats tapes that I watched a million times. (I think our Rugrats tape collection is second only to our Barney tape collection.) I was so insanely happy when they started showing Rugrats on the 90's Are All That, and I've been recording and watching them all. (I've been recording most of the shows on there. It's like reliving my childhood. Do you know how long it had been since I'd seen Hey Arnold? It brings back so many memories.) So recently I've seen a ton of Rugrats episodes that I'd basically forgotten about. It's amazing. The 90's Are All That is one of the best decisions Nickelodeon ever made. It's amazing. Occassionally I'd go on these nostalgic kicks were I look up old cartoons online. Rugrats was always one of the first I'd search for. Now I just have to go to my DVR! (I was also a fan of All Grown Up. I've never understood why so many people seemed to have hated it.)
I want to add Dawson's Creek to this list, but it wouldn't really fit since I haven't watched it in forever. I used to watch reruns all the time, but they quit showing them. (Why must all of the reruns of good shows end?) Now I can't find reruns of it, and I don't own the DVDs (yet). If I could I would watch it all of the time though. I got really into watching the reruns back in middle school, but I never actually watched it when it aired. I think I was a bit young for it then.