The wordpress.org forums use "resolved", but I'm looking for a plugin that adds a button that would mark a topic as "resolved" or "solved". Even if it only adds a class of "solved" via bbp_topic_class. I think it should also close the topic, but that's not specifically necessary. If it did close the topic, then reopening the topic would obviously remove the "solved" status.
I would do this if there were better documentation for bbpress, but I don't have the time right now to go through all the code to figure out the filters/actions I need. Maybe if I'm not doing anything for the week I'll have off between christmas and new years...
If someone does try to make this and needs help, let me know.