Vimperator is a free browser add-on for Firefox, which makes it look and behave like the Vim text editor. It has similar key bindings, and you could call it a modal web browser, as key bindings differ according to which mode you are in.

[ Vimperator :: Firefox Add-ons ]

But I do love vim. I may just have to switch to FireFox as my default browser...

Props to Nick.