Inspired by these posts I started to donate some money to some software projects. Last month was for Mozilla, this month, it's for vimperator.
This addon enable vim-like keybindings on firefox. It's a great project which allow one to almost forego the mouse when browsing the web!
The latest version of firefox (dev-edition and nightly) break the addons, but this should be fixed soon. I've been using it for the past year, 25usd are not that much for the value I get from it.