I just started my Social Bookmarking Exchange forum. Its completely free and I want it to popularize so that people can exchange, buy, sell the social bookmarks on the forum. I mean where will I get the niche members who will exchange the bookmarks. I've seen in freebies section that people exchange bookmarks.
The problem with social bookmarking exchanges is that sites like Digg and Stumbleupon know about it and will more than likely put an end to it soon enough. In fact I read somewhere that Digg is already on top of this. The members that join your exchange may be in jeopardy of losing their accounts ad their sites list in the social bookmark bad bin. Anyway, I think webmaster forums such as DP are your best bet. Maybe try a contest or something to give a viral marketing boost. Good luck with the site.