An often overlooked free source for recent U.S. treaties and other international agreements is the Department of State’s Reporting International Agreements to Congress under Case Act database: http://www.state.gov/s/l/treaty/caseact/
Selected bilateral and multilateral agreements in full-text are available from 1982 through 2008. Unfortunately, the site does not include a keyword search function. The database consists of agreements submitted to Congress by the Dept. of State as required by the Case-Zablocki Act, P.L. 92-403, 86 Stat. 619, 1 U.S.C. 112b. (1972). The agreements appear on this site before they are published in the official compilations of Treaties and Other International Acts Series (T.I.A.S.) and United States Treaties and Other International Agreements (U.S.T.).
Agreements from 2006 through 2008 are available at: http://www.state.gov/s/l/treaty/caseact/
Agreements from 1982 through 2006 are located at the Department of State’s FOIA site: http://www.state.gov/m/a/ips/c24150.htm