Everyone has heard how there's a couple hundred thousand members and only a small fraction of those people are actually active, not only in the forums but also in uploading AMVs, making journals on the main page, and other things.
I really do think that memberships that have been inactive for, say, over two years should be cleared. It will make it a lot easier to find other members (I know there's the members search function but what if you don't really remember the name that well? I've actually gone page by page through the members list by the thousands looking for someone.

) and it will allow new users to have more choices for the names of their accounts (It will clear names that are taken that a new member wants.).