Google Shortcuts 2.1.6
Display all Google services as buttons or as a space-saving dropdown menu next to your address bar. Reach services like Gmail, Google reader, Google maps, Google calendar, and many more in a single click from your browser.
imtranslator
http://imtranslator.net/
Yslow 2.1.0
http://developer.yahoo.com/yslow/
Firebug 1.6.2
http://getfirebug.com/whatisfirebug
Page Speed 1.10
http://code.google.com/speed/page-speed/download.html
Yoono 7.6.2
http://jandan.net/2010/05/20/yoono.html
http://yoono.com/features.html