MAPLight.org, a groundbreaking public database, illuminates the connections...

[HOLLYWOOD]

...between campaign donations and legislative votes in unprecedented ways. Elected officials collect large sums of money to run their campaigns, and they often pay back campaign contributors with special access and favorable laws.

Pretty cool site... with nice help/get started interface

http://maplight.org/video/2/FedTourMay1662007.html

After my search and analysis, through to Sep 07:

Hillary Rodham Clinton

Joe Lieberman

were the biggest acceptors of LOBBYIST and SPECIAL INTEREST GROUPS donations.