This group is run through the Yahoo Groups structure, which provides a location for uploaded files, so the obvious place would be http://games.groups.yahoo.com/group/quackle/ under the Files menu. The administrators of that page would have to set that area to be accessible for uploading by all members. I suppose comments could go in the GCG file as #note .
Note, though, that an alternative is to have a real bug-reporting database mechanism done up, as Mike Thelen does for zyzzyva.
