Social Security Administration - http://www.ssa.gov/online/forms.html
Includes benefit claims forms, benefit claims supporting forms and online transactions (forms that you can complete and submit online).
Student Financial Aid (FAFSA) - http://studentaid.ed.gov/PORTALSWebApp/students/english/fafsa.jsp
Instructions for applying online for student financial aid.
US Passport - http://travel.state.gov/passport/passport_1738.html
Information about applying for a US Passport and the US Passport Application.
US Patent and Trademark Office - http://www.uspto.gov/web/forms/index.html
Forms from the US Patent and Trademark Office, which includes patent related forms, trademark related forms, patent and trademark copy sales forms, and patent cooperation treaty forms.