praktische FF-extension für twitter, kann schnell zwischen accounts wechseln
wasavi is an extension for Chrome, Opera and Firefox. wasavi transforms TEXTAREA element of any page into a VI editor, so you can edit the text in VI. wasavi supports almost all VI commands and some ex commands.
"XBookmarks" for "XMPP Bookmarks". It is the Firefox implementation of XEP-0048: http://xmpp.org/extensions/xep-0048.html. You simply need a Jabber account and you can use it. Currently it is very basic, though functionnal, as the XEP is.
Extension, die nach dem Download eines 3GB Wikipedia Dumps die gesamte Wikipedia offline-fähig macht
Zotero [zoh-TAIR-oh] is a free, easy-to-use Firefox extension to help you collect, manage, and cite your research sources.