I've been looking at the tabs in Firefox, and other browsers like Safari, and while they are overall pretty cool, there's a lot of limitations with them. There's two major improvements I'd like to see:

1. Tabs should be re-arrangable.
2. You should be able to drag tabs off the bar to form a new window automatically, or drag tabs from other windows onto the tab bar to add them to that window.

These features are available with the tabs system in Mac OS X's Adium chat client (and by extension, the Colloquy IRC client, since it uses the same tab interface). Adium's tab code is open-sourced, and I'd really like to see developers implement this code into other pieces of software. Safari would be especially nice.

I think you can already rearrange tabs in firefox. But I would like to see the drag tabs to create a new window in an extension or in the browser itself.

I don't think you can re-arrange them in Firefox. I've tried dragging them, right-click-dragging them, shift-dragging them, control-dragging them, and alt-dragging them, and they won't re-arrange.

When I drag, that little arrow appears. I'm using Firefox 1.5.0.1

It's the same for me

Ah. I wasn't using 1.5.

At any rate, it would be even cooler if you could drag tabs off to form new windows, or drag tabs from other windows onto the tab bar to add them to an existing window.