These sites offer federal campaign finance data. You can download data free from the Federal Elections Commission and can purchase value-added data from the other sites listed. Some sites also offer extensive analysis of the records.

Center for Responsive Politics This site provides searchable databases of federal campaign contributions and federal lobbying, detailed campaign finance profiles for all members of Congress, links to state campaign finance data, and a wide range of other information about money in politics. The center is a non-partisan, non-profit research group that studies the role of money in federal politics. FEC Download contribution data from the 1992, 1994, 1996, and 1998 election cycles. NICAR Federal Election Commission data on CD-ROM, updated monthly. Past cycles are $75 each, or you can subscribe and get the current cycle, updated every month, for $600. Web site describes strengths and weaknesses of the data.