Yeah, I’ve been guilty of some more TV Tropes surfing. I started to make some mental notes of various TV shows which at one time were high profile (either among the general public or amongst certain subcultures), but only a few years later nobody talks about them, no significant cult following has cropped up around them, their reruns aren’t shown anywhere, and basically they aren’t in the consciousness of hardly anybody anymore.
The two examples which came to my mind were Andromeda, and Ally McBeal. Unlike other recent skiffy offerings which have managed to acquire cult followings (Farscape, B5), I don’t sense that there’s much of a rabid community surrounding Andromeda. And as for Ally, this TVTropes page (bullet #5) talks about how quickly she slipped off the scope, going from morning coffee machine fodder at every office to an almost complete non-entity.
Feel free to expand the bounds of the topic to encompass movies which at one time had a much shinier patina (amongst critics and/or the public) than they do now, if you like.