Under Construction, some information is dated.
Codes of Federal Regulation:
ADA regulations for Title I (EEOC):
starts at 29 CFR 1615
ADA regulations for Title II and Title III (DOJ):
28 CFR parts 35 (for Title II) and 36 (for Title III)
New OFFICIAL beta search engine: http://uscode.house.gov/beta.shtml
Old OFFICIAL search engine: http://uscode.house.gov/search/criteria.shtml
Easier to navigate one stop shopping for federal legal info from LLI (Cornell University Law School):
The Americans with Disabilities Act (ADA): The Definition of Disability by the Congressional Research Service, Library of Congress.