Here is a website that has been around for some time, and has a useful directory to many agencies and resources to help people with disabilities find emplyment. Despite the name of this Center, the resources that you can find here are for adults.
National Dissemination Center for Children with Disabillties
"Employers and business groups are trying to stop an Obama administration effort that calls for federal contractors to hire a minimum number of disabled workers and could penalize those who don't by revoking their contracts."