4
i used a multisite modification of my own, but it's still early, so it still requires a good amount of php handling for settings and whatnot
i have all the sites installed using the same physical location of xoops, so i create symlinks (in linux, kinda like shortcuts) for each site to the core set of files.
i set up one site, then copy that site's db tables to all the other sites.
i have most of my db tables shared, except for about 8 or 10, something like that, so it was ~10 tables that exist uniquely for each site.
the rank/avatar tables are shared across all the sites, and since the sites share the same physical files, the ranks/avatars are available to every site
hehe, long explanation for a simple answer