Making Mobile Phones and Services Accessible for Persons with Disabilities from G3ict
A document developed for the UN that looks at the physical characteristics of mobile accessibility.
Seven Steps to Accesible Web Sites
An online book in a similar format to this report looking at accessibility of Web Sites.
BSI Web Accessibility – Code of Practice BS 8878:2010
Describes a process for creating web products.
Henny Swan Blog
Useful list of further reading
A general RNIB paper "Developing Accessible Apps"