The following list of 98 extensions are extensions that have no documentation on wiki based on their SVN name (The name of the directory), If you notice one of yours on there or feel like getting your hands dirty please document it.
I'm not going to hunt anyone down over these, Because I'm just too lazy to look them up in ViewVC and if I know who any of these are, I would of already bugged you on IRC.
Notes: * Some of these may be incorrect if it's documentation exists at another name (For example: If it has spaces in the name) but I attempted to fix most of those. * (W) indicates extensions that exist in the current (1.16wmf4) deployment branch * For a nice click able list: http://www.mediawiki.org/wiki/User:Peachey88/Sandbox/WMFext * Some of these might not actually be extensions
The List: * Extension:AdvancedSearch * Extension:Aggregator * Extension:AjaxTest (W) * Extension:BadImage * Extension:CategoryFeed * Extension:Citation * Extension:CodeBrowse * Extension:CodeTest * Extension:CommunityApplications (W) * Extension:CommunityHiring (W) * Extension:ConditionalShowSection (W) * Extension:ContactPageFundraiser (W) * Extension:Crosswiki * Extension:DonationInterface (W) * Extension:DontSwitchMeOver * Extension:EditMessages * Extension:EditSectionHiliteLink * Extension:Entities * Extension:ExternalPages (W) * Extension:FastStringSearch * Extension:FileSearch * Extension:FootNote * Extension:FormPreloadPostCache (W) * Extension:GeoLite (W) * Extension:HTTPRedirect * Extension:Hanp * Extension:HoneypotIntegration (W) * Extension:HtmlUi * Extension:InlineEditor * Extension:InlineScripts * Extension:Interact * Extension:Invitations * Extension:LastUserLogin * Extension:LatexDoc * Extension:LdapAuthentication * Extension:ListChangedArticles * Extension:LocalFileLink * Extension:Logo * Extension:METIS * Extension:MWBlocker * Extension:MakeDBError * Extension:MessageCommons * Extension:MogileClient * Extension:MwEmbed * Extension:NavigationPopups * Extension:Negref * Extension:NewUserNotif * Extension:NewsChannel * Extension:Nogomatch (W) * Extension:NopurgeRC * Extension:NssMySQLAuth * Extension:OtherSites * Extension:ParserWiki * Extension:Piwik * Extension:PlayerStatsGrabber * Extension:PoolCounter * Extension:Preview * Extension:PrivateNamespaces * Extension:ProfileMonitor * Extension:RSSNews * Extension:RdfRedland * Extension:SVGEdit * Extension:SVGZoom * Extension:SandboxMessage * Extension:ShowProcesslist * Extension:SisterSites * Extension:SpecialFileList * Extension:StarterWiki * Extension:StaticWiki * Extension:StrategyWiki (W) * Extension:SwarmExport * Extension:Syslog * Extension:TidyTab * Extension:TimedMediaHandler * Extension:Todo * Extension:ToolserverTools * Extension:Tooltips * Extension:Throttle (W) (Not in main /extenstions directory) * Extension:UKGeocodingForMaps * Extension:UnicodeConverter (W) * Extension:UploadFromCommons * Extension:UserThrottle * Extension:VariablePage (W) * Extension:WikiMiniAtlas * Extension:Wikidata * Extension:WikimediaMobile (W) * Extension:WiktionaryInflection * Extension:auth * Extension:examples * Extension:geo * Extension:icpagent * Extension:normal (W) * Extension:pecl-proctitle * Extension:php * Extension:phpbbData * Extension:transliterate * Extension:uniwiki * Extension:zhdaemon