I just discovered this fantastic little application for FireFox that helps people with severe mobility impairments. Historically, switch access users haven't been able to get to the toolbar of their browser without help from someone else, so even simple actions like using the 'Back' button have been impossible. One of the best tools on a website for this group of users is the breadcrumb trail which helps them navigate back to points in their browsing history, but many sites don't feature these and may leave some users a bit stuck.
The Hawking toolbar allows some simple controls to be available to the user including the essential 'Back' function. It's free to download and has some really useful features such as grouping links based on proximity to each other and switching between groups rather than tediously highlighting each individual link. It will then switch between links in that group. Very neat.
You can find out more about the toolbar from the Oatsoft website.
While we're talking about tools for people with mobility impairments, I noticed Karl Dawson posted a link that he found which featured people using software called 'Keystrokes'. There's a whole bunch of videos on there that are mind boggling. I never imagined that you would be able to play first person shooters with only your thumb but you can, and people do.