Depends on how the site in question most often refers to itself. Using this site as an example is awkward since we sometimes refer to ourselves as Resource Zone, sometimes as Resource-Zone, sometimes as Resource-Zone.com, sometimes as the ODP Public Forum... It really didn't have a name in the beginning beyond the somewhat general description of "A Public Forum Sponsored and Moderated by ODP Editors". It's the URL that has led to it being called Resource Zone (or some variation thereof). Quite a few sites end up being listed with the URL (and it wouldn't be wrong for this one in particular to be listed as Resource-Zone.com).
I presume you have a specific site in mind for your question -- why not come right out and ask about it instead?