Nowadays, almost everybody already know how good is firefox. Not so many know about a very good extension for it, Google browser sync. It keeps all your browser's personal information into your Google account, and synchronizes it in any computer. Very useful when using more than one computer (home and work...), or when reinstalling your system.
Debian doesn't include firefox itself, it's available a rebranding branch called Iceweasel. When trying to install the extension in this application, the page doesn't detect that Iceweasel is a firefox 2.0 compatible application, and raises and error. Solution, just click here.
UPDATE: Some other application doesn't detect your browser (for example when changing your profile's picture in Google Groups. To fix all those problems just type about:config, search general.useragent.extra.firefox and change it's value from Iceweasel/2.0.0.1 (or your version) to Firefox/2.0.0.1.