The Center for Public Integrity has a public database online, where users can find out which financial and business interests have ties to state politicians.

From the site –

State legislators directly influence the lives of all Americans. The 7,400 lawmakers in state capitals across the country passed close to 40,000 laws in 2005 alone and spent an estimated $1.3 trillion in taxpayer money in the same year. Ever wonder what outside financial interests legislators making these decisions might possess? Find out more about the potential for conflict of interest and view legislators’ actual disclosure filings by selecting a state.

The site is a great resource for everyday citizens as well as campaign / election researchers.

You can search the database @ Our Private Legislators.