I actually went to school to learn to build a site similar to this (2003, not sure how many tutorials there were then, but I didn't know of them anyway). Though my inspiration came from loving to camp and canoe/white water raft and no friends of mine liked that outdoorsy stuff.

I also didn't realize this site was already out there, but if it was dating/sex related by that time, I wouldn't have known it could be used for that.

FWIW, there's another site I think similary created for meeting people nearby as friends (Meetme.com) that has also turned into a sex/hookup app.