http://www.fxc.btinternet.co.uk/assistive.htm - FX Software - Assistive Software - A selection of free assistive software tools for Microsoft Windows.  Most of them can make it easier for people with visual or motor impediments to use the keyboard, mouse or screen.

http://www.assistiveware.com/products.php - Features a variety of assistive software, available for testing on a try-before-you-buy basis.

http://www.ed.sc.edu/caw/toolboxat.html - Web Toolboxes for Educators - Vendors for Software & Assistive Technology - A collection of links to many Assistive Technology software vendors.

http://www.oatsoft.org/ - OATS (Open Source Assistive Technology Software) A collection of open-source assistive software, including both free and non-free programs

http://www.inclusive.net/ - ICTS (Inclusive Consultancy and Training Syndicate) - Includes resources for educators who would like to make better use of assistive software and other inclusive technology.  (Also check out their list of useful sites at http://www.inclusive.net/resources/sites/useful_sites.shtml )

http://www.microsoft.com/enable/ - Microsoft's Accessibility site - Includes information about using accessibility features in Microsoft's products, including Windows, Office, and more.  For example, do you already know about Windows' built-in screen reader and screen magnifier features?

http://www.widgit.com/ - Widgit - A software company that offers a variety of (non-free) software programs that aid in the learning and teaching of communication.

http://en.wikipedia.org/wiki/List_of_screen_readers - Wikipedia - List of Screen Readers - A list of screen reader (text-to-speech) software, both free and commercial

http://www.ncatp.org/Resources/Freeware.html - North Carolina Assistive Technology Program - Freeware - A list of links to free assistive software programs in several different categories, including software for those with visual impairments, keyboard and mouse difficulties, and more.