I've searched for them, yet they all seem old & unused. I would've thought, with the number of people starting forums, some must want it! Any ideas why not?
Have you tried using Post Fusion? I used it with my last forum to get some posts happening and it worked well.
Many people are so interested in getting posts on their own forum that they aren't willing to put in the time to post on other people's forums. A bit short sighted, I think, but it's the truth. However, you may be able to find some people to exchange with here on DigitalPoint, in the trade section.