Follow the Money

This purpose of this organization is to "...reveal the influence of campaign money on state-level elections and public policy in all 50 states."

MAPlight

A "...public database, illuminates the connection 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." [from the site]

OpenSecrets -

"Nonpartisan guide to money’s influence on U.S. elections and public policy. Whether you’re a voter, journalist, activist, student or interested citizen, use our free site to shine light on your government. Count cash and make change."  [from the site] 

USA Spending

A  database of U.S. Federal government awards to contractors and grant recipients. Mandated by the Federal Funding Accountability and Transparency Act (Transparency Act) of 2006.  The data is searchable by many fields; check out your congressional district.