Thanks for responding. And thanks for joining Side 7.
Back in its heyday, Side 7 was one of the few galleries on the net, and it enjoyed a lot of activity. We have a no-porn policy which appealed to a lot of people. High schoolers were definitely our largest demographic, as they always seem to be on the bleeding edge of social technology.
The drop in our activity and membership levels can be directly attributed to DeviantArt, to be honest. They came on the scene in the early 2000s, had an extremely liberal set of rules, no upload limits, and tonnes of popularity-driven features. Since then, numerous DA clones have popped up. As of right now, the gallery space is saturated on the internet, with those having the least rules and administration and the most popularity tools being the most successful.
We've got a Facebook page, and while there are members to it, it remains largely unused. Same with our IRC channel, LiveJournal Community, and site features. I'm continuing to work on new features which are similar to many popularity-based tools, but (hopefully) done in a way that doesn't turn Side 7 into just another farm for popularity contests. I'd like the site to remain about the art, and not about who's got the biggest fan-base.
Unfortunately, that stance seems to be the kiss of death, but we're still fighting. We'll see how things go.
As far as the timeline between 2001 and 2003 being the most art, we had launched a new version of the site, and it had a lot of new tools. We also had no upload limits. Unfortunately, the lack of upload limits promoted the uploading of a lot of "junk" artwork (doodles from the margins of people's math tests, stuff with descriptions of "I hate this pic I drew, but I'm going to upload it anyway" and such). The volume of lower-quality images was vastly overrunning the quality images, so we instituted the upload limits to encourage people to be more selective about what they uploaded.
That turned out to be a double-edged sword, and I think was the largest factor in our losing memberships and activity. I still stand behind it, though, since the quality of what is upload is vastly improved. We're bringing in features that allow people to "buy" additional uploads with Account Credits, which are earned through site activity.
We'll see how it all turns out. :/