foXpose - Expose for Firefox
Exposé is one of the best and most useful feature of the Mac OS X. Exposé was introduced in Mac OS X 10.3 (Panther). With Exposé you can access any open window with a single keystroke.
Viamatic software created a very cool Firefox extension called foXpose. This extension enables a small button on the left side of the firefox browser which, when clicked, will create thumbnails of your open tabs in the browser window.
The extension works on Firefox both on Mac OS X and Windows, I haven’t tested the extension on Linux version.
Same feature is also offered by Shiira, the WebKit based browser.