Homestar Runner made me laugh but it was a kind of quirky "kids' humor for not-quite-adults" that I laughed at. Watched a lot of eBaumsworld junk around 2003 too. Of course that stuff's still around (Neil Cicierega has moved on to lots of stuff), but God knows who's still looking it up or laughing at it.
In 1995-98 I used to get on "secretive" websites like ftp.spies.com and read through stupid text files containing anecdotes from the 80s about punk underground culture and anarchy and spraypainting and vandalism and stink bombs and stupid crap like that. I planned on detonating a massive stink bomb in my school but I didn't really know how to make one and besides Columbine happened so my life probably would have been ruined. I also liked to read lists of alcoholic drinks that I'd never try either.
IMDb forums - Eghn, they moved too fast and were too full of garbage. Moviechat is slower and better.
Napster - Well I don't *miss* it really but I do have some memories....Why yes, mr. history teacher! Download "Big Balls" by AC/DC and play it in class! You'll be fine!
Any old, well-stocked, fast-moving message boards that I posted on, including this one, will be missed.