> ruvi does this already.
> http://thekode.net/misc/ruvi01.png
> shows 4 buffers being edited simultaneously. You can change the active
> buffer with <C-j>/<C-k> (small snippet needed in the ~/.ruvirc to set
> the keybindings).

A funny anecdote: 

After viewing the screenshot, I tried to close the browser tab with :q.