Re: Friendster-like features
You can allow registered users to create Image Galleries and File Galleries and only they by default can upload content into them. THose can be setup through admin->Groups
All Wiki pages can be categorised. So providing you have a suitable category base setup in TikiWiki, then your UserPages can be categorised accordingly.
There is a user list ;) http://tikiwiki.org/tiki-list_users.php or click Community on the menu