SW Tickle for sure. That guy rocked. I remember he put up a series of Realtickling pictures where a maid gets her sexy heels removed which I feel is a damn shame I never saved.
There was also a site called Arkham which I really liked. My adoration of HP Lovecraft notwithstanding, it had very diverse content, and a cool bat animation. You could download photos, clips, drawings and even audio from there. It was also the very first tickling site I ever encountered, so it will always remain special for me.
L'Initiation (in French) was a milestone in the French speaking world. It was amazing.
Venray's site, for its high-res photos which took forever to load at a time most people including me had only a 56k router. Plus Venray looked strikingly like my high school math teacher.
Man I miss the old Internet, pre-wikipedia! I loved the anarchy, the raw creativity, the very personal presentations (often in black with gif animations) which told a lot about the author. Fan sites really looked different from each other, and people created content for all kind of stuff. Now everything is a little bit too standardized for my taste.