Visually Impaired users

Hi,

I'm doing some research at Uni which involves designing systems to aid visually impaired users of devices such as PDA's and mobile phones.

Part of my project is to research current technologies and assess the effectiveness of those technologies.

I was just wondering if anyone knows of any software available to aid visually impaired users of a pocket PC?

Also, are there any visually impaired users that can offer any suggestions to make things easier to use?

Many thanks,

Adrian.