Topic: eTrainingLog Forums
I have a site that allows people to track their training (biking, swimming, running, etc) in a log/journal. You can have common workouts, track your miles, and more. The format is much like a blog and people can leave comments on the public entries.
That code was all done from scratch on my own.
We now have forums as well, and those are running PunBB. Will slowly add/change various things over time, but for now just have it up and will see how it goes from there for a bit.
http://www.etraininglog.com (the forums are at http://www.etraininglog.com/forums )