The Government Publishing Office's online version of the U.S. Code, with versions back to 1994. Titles, chapters, or individual sections can be downloaded in PDF.
Current and historical editions of the U.S. Code, in addition to earlier compilations of federal statutes. This is the source to use for cite-checking, because its PDFs mirror the printed volumes and supplements.
Information by and about the U.S. Congress: documents and reports, Legislative Histories, hearings, and members and committees. If you're researching legislative history for a particular law, try ProQuest Legislative Insight.
Searchable legislative history information and texts for congressional bills 1989-date, as well as information on older bills (1973-date) and the Congressional Record 1989-date.
Hundreds of compiled legislative histories for specific acts in PDF, as well as Sources of Compiled Legislative Histories with references to other printed and online resources.
U.S. Congressional Documents and Debates, 1774-1875. Includes access to bills and resolutions, House and Senate Journals, and the early Congressional Record and its predecessors.
Access to CQ Magazine for news of congressional activity, as well as research reports and reference works such as Politics in America (information on members of Congress and their districts).