Everything Wiki ;-)
Below is a listing of all the public mailing lists on lists.wikimedia.org. Click on a list name to get more information about the list, or to subscribe, unsubscribe, and change the preferences on your subscription. To visit the general information page for an unadvertised list, open a URL similar to this one, but with a '/' and the list name appended. List administrators, you can visit the list admin overview page to find the management interface for your list. WikiLabs. Wiki-Incubator! WikiBugzilla. TiddlyWiki - a reusable non-linear personal web notebook. Wiki data compiler. DBpedia is a crowd-sourced community effort to extract structured information from Wikipedia and make this information available on the Web.
DBpedia allows you to ask sophisticated queries against Wikipedia, and to link the different data sets on the Web to Wikipedia data. We hope that this work will make it easier for the huge amount of information in Wikipedia to be used in some new interesting ways. Furthermore, it might inspire new mechanisms for navigating, linking, and improving the encyclopedia itself.