experimental
Firefox 4 may be getting tabs in title bar option

As with Google Chrome, your tabs will only move to the topmost area of the window when maximized. The feature has yet to be delivered to the Firefox 4 nightly builds, but you can download experimental versions from developer Bill Gianopoulos. Windows and Linux versions are available at the moment. Gianopoulos states "These builds are essentially the same as the corresponding Official Trunk Nightly Builds" but notes that his builds include "not yet landed fixes for some MathML issues, and User Interface changes planned for Firefox 4, as well as bugs that I am currently working on or find particularly annoying."
Chrome's About:Labs Renamed to About:Flags, Adds a Warning

If you're a fan of tweaking Chrome's experimental, under-the-hood features using the about:labs feature, here's a change worth noting: about:labs is now about:flags. More »
Google Chrome's about:labs becoming about:flags, kill switch added

Today, the change has landed in Chromium and will no doubt be pushed to Canary shortly. Now called about:flags, the page sports the trefoil (internationally recognized as a warning against radiation) and a bigger, scarier warning. "Please proceed with caution," the intro concludes.
In addition to the name change and new cautionary text, a command line switch has been added to allow users to launch Chrome with all previously-enabled experimental features disabled: --no-experiments. Should you happen to encounter problems browsing after enabling a feature or two, simply add the switch to your launch command and you're back to the stock set of Chrome features.
More experimental features (and DANGER!) on the way to Chrome's about:labs page

Bleeding-edge Chrome users -- especially those using Macs -- have at least one very good reason to like Chrome's recently-added about:labs page. First and foremost, it provides an easier way to enable and disable features that were previously buried behind command line switches.
In a posting on the Chromium-dev board, Google's Ben Goodger has some encouraging news for about:labs fans. Goodger wants Chrome developers to get their experimental features added to Labs, so expect to see plenty of future additions as Googlers tinker.
At the same time, Goodger wants to make it more clear that Labs features are experiments -- meaning users could very well mix the "chemicals" improperly and have Chrome blow up in their faces. That's certainly the case with Chrome's accelerated 2D canvas switch in the current Dev channel build.
As such, there's a re-name coming so that the page sounds a bit less friendly. Perhaps about:danger? about:itsatrap? Maybe they should also change the background color to red or slap a sign on the page...
Labs – Crazy Experimental Stuff Now in Google Chrome Canary
I enjoy using Google’s Chrome Canary build so that I can try out the latest features of Google Chrome. Today, Canary’s update included the Chrome Labs page. This feature has been available for a few days, but only in the Chromium code base. To bring up the Labs page, you have to open a new tab and type: “about:labs” (without the quotes).
Google may say that it’s “Some crazy experimental stuff”, but so far, it’s not that crazy. The only experiment available right now is “Side Tabs”. Once enabled, you can right click on any tab to enable or disable it. Here are two screenshots below to show you what it looks like.
As you can see, the Side Tabs really change the look of the browser. I miss the rounded tabs and I’m guessing that I won’t use this new feature often. The reduction in screen width isn’t worth the ease of navigation unless you have lots and lots of tabs open.
While I’m not excited about the Side Tabs lab experiment, I am happy to see the Labs page in Chrome Canary. At least I can hope they’ll stop using those stupid command line switches now.
Labs Extension: If you don’t like having to type “about:labs” in a new tab, there’s a Labs Chrome Extension that let’s you click on a Labs icon to bring up the Labs page.
More New Features: Be sure to check out three other new features in Chrome 7, Chrome Web Apps, Voice Recognition and Hardware Video Acceleration.
Video: TabCandy is coming -- and it's like a virtual desktop manager for Firefox

TabCandy is a bit like a full-featured virtual desktop manager -- think of Web pages as applications and browser windows as desktops. Install TabCandy and a button is added to your Firefox toolbar. Click it, and you'll see a view like the one above. You can group tabs, label them, and move tabs between groups with a simple drag-and-drop.
The layout is totally customizable -- resize group boxes however you want and reposition them, and the thumbnails automatically resize and re-order themselves. You can also add a new tab to a group by clicking the icon in the bottom-left corner. Click a thumbnail, and the page zooms into the foreground.
Want to see TabCandy in action? Check out my brief screencast after the break!
The extension is still unfinished, but TabCandy has come a long way since I first checked it out -- and it's definitely fun to play with now even if it's not quite ready for prime time. You can find the TabCandy.XPI on Mozilla's server (it's near the bottom of the list).
Who knows -- you could be looking at the tab management interface for Firefox 4!
(worth noting: Mozilla's Aza Raskin has gotten in touch with Sebastian and reports that the .XPI is somewhat out of date. Still, it's the easiest way to play with TabCandy if you're so inclined.)

