Facebook, PayPal, and Google have reward programs for advising them of bugs in their systems.
(The bug has to be a potential security vulnerability, but the rewards can be substantial. Facebook pays a minimum of $500 for qualifying bugs, while Google pays from $100 up to $20,000! PayPal is coy about what it pays.
Microsoft, encourages people to report bugs, but it doesn't fork out any money at all. Instead they "acknowledge" the person who reports it. I guess that's how Bill got to be so rich.)
