I heard You can clean using coke. http://youtu.be/z7OdX42NjWQ
Edited/Updated :
1.Have a new bottled coke - which has carbonated gas.
2.Pour coke on the rusted surface.
3.Give it a few minutes, and then take a piece of sponge or a coarse cloth and rub off the rusted surfae.
4. NOTE : Only coke which has the carbonated gas works. If it does not have the gas, it does not work.
@michaelpri, @subjectivist - Thank you and I will remember to write better answers from the next time.