For the mobility challenged
For people who have difficulty handling the keyboard and mouse, there are some specialised tools. Users who cannot handle the mouse can control their mouse pointer by head movements, which are captured via the Web camera. Enable Viacam is an open source, free software that doesn’t need any additional hardware. Enable Viacam can be downloaded from http://eviacam.sourceforge.net/index.php. There are versions available for Windows and Linux distributions.
For people with severe motor disabilities, there is an extension called Hawking Toolbar, which is named after the famous physically challenged scientist, Stephen Hawking. The Hawking Toolbar enables those with severe motor disabilities to access the Internet. The extension presents the links in the Web page to users in a sequential manner, and users can choose their special devices.
An extensive list of open source accessibility tools can be found at: http://www.oatsoft.org/Software/listing/Repository