If it wasn't AOL chatrooms and groups it was small forums with a dedicated, if minimal, community. The first actual websites I can remember RPing on were probably GameWinners in their Clubs and Clans section where I tried, rather unsuccesfully, to get an RP based on some book series called Broken Sky going. I still remember when a Clan I was in got into a Clan War with one of the top Clans on the site and our Clan leader embarrassed us by putting up like eight words in an RP in what was meant to be a showcase of RP ability. 

From there I moved around a lot, settled on Quizilla's forums for a while. I fell off of forum based RP around the time those forums up and died, floated around some places, some 18+ forums and communities, and then somehow I got lost and no one here has given me directions home.