Social Security Administration
Social Security Administration: 2007 Annual Report of the Board of Trustees
This is an annual report issued by the SSA in which they evaluate the state and health of the Social Security program and make projections. It is also in PDF format and there is a summary available.
Social Security Administration
Ssa: Supplemental Security Income Info
Information on SSI from the Social Security Information. THE place for information on laws and policy of this aspect of the US program.
Social Security Administration
Social Security Online: History
This site addresses the history of social security. There is an invaluable amount of information on this site (timelines, audio clips, etc.).
Other
Law info.com: Social Security Disability Verified Attorneys
This resource on Social Security benefit programs explains the differences between Social Security Disability Insurance (SSDI) and Supplemental Security Income (SSI) programs.