If you have problems with your eyesight, or you look after the computer of someone who does, then Vinux is definitely worth a look. It's a customised version of Ubuntu Linux for those with impaired sight. It includes all the basic Linux functionality, but customised for ease of use.
There are 2 built-in screen reader (text to speech) apps, 2 screen magnification utilities, and it works with third party Braille displays straight out of the box. It's also easy to change screen colours, font sizes, etc.
Vinux is a large download, of around 700 MB, and is available in a number of different download configurations from the main www.vinuxproject.org web site. You can get bootable images for both CD and USB, and there's a Live option that allows you to run the operating system from a CD without installing anything to the hard disk.
Vinux is free, but the developers ask for a donation if you find it useful.