Back in Oct 2011 I added to the "Fan mission listing by type-thread" with a list I was trying to finalize for the Thief Wiki: updated list of tags.
I didn't get a lot of responses, to say the least, I guess people's ambition toward tagging wavers.
The Forums tagging is a bit unorganized, since it encompasses all Forums. Looking at this thread, there are almost too many tags. Sorry for hijacking the thread, but I think the wikis implementation is easier to use.
The cloud on the wiki can be partially seen here(at the bottom), it is not fully searchable yet, since I wanted to finalize the tags first, but the final cloud would look like this.
You can see how the tagging work on a FM page and how they are edited here.