Oleg Popov has recently started a new wiki called WiKi4All, which aims to be a catalog of wikis, where all existing wikis are listed in certain categories.
He's actively visiting loads of wikis and leaving a message for the maintainer to add his/her wiki to WiKi4All. I have already added Unmaintained Free Software there, and Crazy Hacks and Holsham Traders will follow soon.
Holsham Traders, by the way, is a realtime multiplayer trading game written in Ruby, which I'm currently developing (more on that later).
Mattis Manzel has brought to my attention the so-called WikiNode project. The basic idea is that every wiki should have a page called WikiNode, which describes what the wiki is about and provides links to the WikiNode pages of related wikis.
I have added a WikiNode page to both of my wikis, Crazy Hacks and Unmaintained Free Software (besides other new stuff such as a forum, image license templates and more).
The Unmaintained Free Software wiki is now online and has been declared by me to be the authoritative source for unmaintained or orphaned Free Software projects. The old website is gone, but I will port the old contents to the wiki step by step. Please bear with me.
All content of the wiki is licensed unter the terms of the GNU FDL.
Again, if you know of any unmaintained project or want to take over maintenance of a currently unmaintained project, go ahead.
Today I have moved my site Unmaintained Free Software to another server, again. The URL didn't change, so no need to update your bookmarks or anything.
In the next few days or weeks, I'll be migrating the whole content of the database to the new Unmaintained Free Software Wiki, which is in beta stage right now, but you can already play with it and add/change stuff.
As soon as the content is migrated, I'll remove the old site and the wiki will become the authoritative source.
I hope that moving to a wiki will, on the one hand, foster collaboration and encourage people to contribute, and - on the other hand - simplify and speed up the management of the site itself.
All content will be licensed unter the terms of the GNU FDL.
So, if you know of any unmaintained project or want to take over maintenance of a currently unmaintained project, go ahead.