Firefox Home Dash experiment offers a radical new UI for your Mozilla browser
Hover over the Firefox logo in the top-left of your window or press Ctrl+T, and Dash will appear. The Firefox Awesome Bar floats to the left, offering all the same functionality you find in the browser right now. It'll search your history, bookmarks, or submit your query to any search engine with the click of a favicon. The right half of your Dash is populated by your currently open tabs (in a strip along the top -- pinned tabs on the left) and frequently visited pages (shown below). Sites you visit most often will be placed in one of the four larger, central slides. As you can see from my screenshot, Dash doesn't always render thumbnails -- but this is the first release of an experimental add-on, so we were expecting a few bugs.
When you pause on a thumbnail, Dash will display it in the background. Click the page image, and it zooms into the foreground. Previews also appear when you Ctrl+Tab or Shift+Ctrl+Tab to change your active tab. You can also drag tab thumbnails to re-order your browser tabs.
Dash is interesting to play with, though there's definitely an adjustment period required. Unless you're used to browsing in full screen mode, it's a bit odd looking at Firefox with practically no chrome. Still, the only UI element I really missed was the tab bar -- I prefer having something to click on to switch tabs over paging through them with hotkeys or invoking Dash and clicking a thumbnail.
If you want to give the add-on a try, download Firefox Home Dash from Mozilla. Firefox 4 is required, and you can start using Dash right away -- it's restart-free!