OpenDyslexic is a new open sourced font created to increase readability for readers with dyslexia. The typefaces includes regular, bold, italic and bold-italic styles. It is being updated continually and improved based on input from dyslexic users. There are no restrictions on using OpenDyslexic outside of attribution.
Your brain can sometimes do funny things to letters. OpenDyslexic tries to help prevent some of these things from happening. Letters have heavy weighted bottoms to add a kind of "gravity" to each letter, helping to keep your brain from rotating them around in ways that can make them look like other letters. Consistently weighted bottoms can also help reenforce the line of text. The unique shapes of each letter can help prevent flipping and swapping.
OpenDyslexic also takes a different approach to italic styles. It is generally recommended that italics be avoided in reading material for dyslexia. However, instead of taking the normal approach of "slant x% for italic,"OpenDyslexic's italic style has been crafted to allow for its use for emphasis while maintaining readability.
You can download the font from here
The same company also produce a free web browser designed for people with dyslexia for the ipad, iphone, iPod Touch.
You can download the app from the App Store here