I often drift away from a ton of shows. Those I can think of off the top of my head:
Glee: I liked the musicals and the singing. I liked Jane Lynch's character too. I listened to / downloaded some of the sounds. Sometimes, I even preferred the Glee versions! However, I also thought the drama was becoming repetitive. XD;
My Little Pony: This show is a major-time killer and can be addicting. I was practically marathon-ing it and then... boom! I stopped watching it. I have no desire in watching their routine adventures again. I gotta wonder, did the little one, Apple bloom, ever get her cutie mark? Yeah, that was like, the only major reason why I kept clicking the next button. :(
Naruto: I loved this show when it first debuted. However, I had to stop watching it after nearly 100 episodes... I just can't follow a series for that long. My limit is about.. 80 episodes? Laziness strikes again.