Information related to the various screen readers

Screen Reader Website Free / Commercial
Non Visual Desktop Access (NVDA) http://www.nvda-project.org/ Free
System Access To Go http://www.satogo.com/ Free
WebAnywhere http://webanywhere.cs.washington.edu/wa.php Free
Hal http://www.yourdolphin.co.uk/productdetail.asp?id=5 Commercial
JAWS http://www.freedomscientific.com/jaws-hq.asp Commercial
Supernova http://www.yourdolphin.co.uk/productdetail.asp?id=1 Commercial
Window-Eyes http://www.gwmicro.com/Window-Eyes/ Free