I work to improve several mediawiki extensions.
I've added some of them on http://sourceforge.net/svn/?group_id=192908 subversion repository in order to facilitate community work on them.
Many of them were hosted on personal sites and from time to time some of them god vanished, so using sf.net would be safer.
If you want to do contribute feel free to contact me or other member of the project in order to gain write access to the repository.
Extensions already with code ported to subversion repository:
- Extension:Glossary - The version checked into SVN is old. There is a newer, better version available. Please contact me to resolve this or just use the code from: The old extension page
- Extension:CategorySuggest
- Extension:Google Maps
- Extension:Poll
- Extension:GoogleCalendar