The referrer string of a recent spammer of the chongqed.org wiki led me to the homepage of the "spinner wiki" engine.
I'm not linking to it since it already seems to be a GhostTown. But the URL is http://spinner-wiki.sourceforge.net/ if you want to have a look yourself.
Not only doesn't it seem to have any spam prevention mechanism (at least none that works), it also doesn't offer the possibility to view the history of pages so you could revert to a spam-free version. Besides, the last release dates from July 2003.
It's bad enough that people install wikis on their sites and then forget about them. But to see that a wiki engine is created and then forgotten is really depressing.