And one step further is to have vi-like binding for navigating the web, switching tabs etc.

Vimperator and its recent fork Pentadactyl do this for Firefox, there's similar (though when I looked into it, less advanced) add-ons for Chrome/ium too, I think the one I tried was called Vimium.

I was worried using such an invasive add-on would trip me up with Firefox's new rapid release schedule, particularly as I jumped to Pentadactyl because it supported version 4 first/better) but I'm up to Firefox 6 with no problems as yet.