I wrote an open source app (BugTracker.NET) and I host it at Sourceforge. It doesn't have a plugin architecture per se, but there are ways to tweak and extend it. For example, a prettier css file, or a useful SQL snippet. People ask me, "How can I share this with other BugTracker.NET users?" and so far I've just been telling them to put it in the Sourceforge RFE tracker. Not that useful.
So, I want to set something up, maybe like a wiki, maybe, but with the ability to upload files? Something that can function without too much of my involvement, but that I can still moderate to get rid of spam, I guess?
I'm not talking about bug fixes that I want to apply to the mainline. I'm talking about things I would NOT merge into the mainline, but that I would still want to make available to others.