A major improvement would be that once you type something (for example GIT), and then pause for a few seconds, you can begin typing something else (such as XKCD).
I started using it. I liked it. But, I use Space button to scroll down. You are eating that away. Felt very irritating. Your 'shortcuts' should not mingle with the existing ones, at least, the most used shortcuts like SPACE button.
If I try to type to 'wiggle' a link in Google search results, it always just continues typing in the search input box.
While using the escape key to 'escape' a 'wiggle' makes sense, setting it to backspace makes it easier to access and also makes sense, or allowing users to configure which key to exit a 'wiggle'.
It's a tradeoff, actually. I used to use Vimium for following links, but I made this because I feel it's a little more natural than hitting 'f' and then typing an arbitrary code next to the link you're looking at. Instead, you can just type exactly what you see immediately. It's really just a personal preference, I feel.
Plus, DeadMouse usually finds the link within the first two characters, so it's not any more typing than Vimium.
That's pretty clever, I think this should be implemented natively in browsers. It's nice that it's bound only to the visible part of the page too.
But let's face it, if web devs were conscious about keyboard usability we'd at least see tabindex html property used sometimes, and it's been around for a while.
[1] http://5digits.org/pentadactyl