Thanks dude for creating and maintaining the post. Useful for everyone :)
Few more
Media player extension
http://www.webupd8.org/2011/11/try-new-mint-gnome-shell-extensions.html
Pidgin Integration
http://www.webupd8.org/2011/10/native-gnome-shell-notifications-for.html
Thunderbird extension
https://github.com/tanwald/gnome-shell-extension-thunderbird-integration
Workspace Switcher Extension,Alternative Status Menu GNOME Shell Extension,SystemMonitor GNOME Shell Extension,Apps Menu GNOME Shell Extension,Places Menu GNOME Shell Extension,User-Theme GNOME Shell Extension,Alternate Tab GNOME Shell Extension
http://www.techdrivein.com/2011/10/7-best-gnome-shell-extensions-install.html
Many standard extensions can be easily installed thr ppa's
http://www.webupd8.org/2011/10/official-gnome-shell-extensions.html
I am sure some day we will have a chrome web store sort of thing for gnome shell extensions too , until then we have to live maintaining a list like these :P (or some one might have already created a better blog having the list)