Get rich by suing companies
It seems private individuals in IL can sue online retailers, that don't charge local taxes, on behalf of the state. If the individuals win, they can collect up to 25% fines and back taxes that the online retailer has to pay to the state. Luckily it seems other states caught on and have changed the law to prevent this in other states.
http://www.post-gazette.com/pg/05287/588742.stm
http://www.post-gazette.com/pg/05287/588742.stm

