Congressional Record - Available from 1789-1997 in the Digital U.S. Congressional Serial Set, this provides access to the text of congressional bills, debates, and recorded votes on legislation.
Use the Congressional Globe for the text of congressional debates from 1833-1873.
The Library of Congress' American Memory Project's Century of Lawmaking site contains the Congressional Record from 1873-1874 and other important congressional documents including the House and Senate Journals from 1789-1875.
Biographical Directory of the United States Congress 1774-Present (Features succinct biographical portraits of members of Congress and bibliographic references.)
CIS Index to U.S. Executive Branch Documents 1789-1909 HSSE REF 351.73 C497 1990 (Indexes U.S. Government documents which were not published in the Congressional Serial Set. These documents are not part of the print Congressional Serial Set! However, they are part of Proquest's Online Congressional Serial Set)
LexisNexis Academic (Includes the text of federal and state court opinions. Federal court opinions will be from 1789-present and state court opinions from the year the state entered the Union.)