I stumbled upon this website the other day. I didn't find any money for myself, but I did find over $500 for other people that I know.
This site lists unclaimed property that may be waiting for you for any various reasons: unclaimed payroll, rebates, tax refunds, etc.
You can always go to treasury website for the state that you live in (or other states that you have lived in) and make your claim there. You shouldn't have to pay anybody anything to claim what is yours either.
http://www.missingmoney.com/
Good luck!