Many web2.0 sites have great potential for students with disabilities. Many of these sites help meet the concepts of Universal Design for Learning (UDL). UDL is a framework curricula that enable all individuals to gain knowledge, skills, and enthusiasm for learning. Using multiple means of representation, multiple means of action & expression, and multiple means of engagement you can create lessons & curriculum that all learners can participate in.
http://www.freetech4teachers.com/2010/02/web20-students-with-disabilities.html