You could probably make some money on a "proof validation service" where you charge all of the crackpots who think they've solved P!=NP to validate their proof.
Or, if you just happen to find an error, send that back. But the service is free if you don't!
From talking to the mathy-side CS faculty in my department (UofC), the crackpots all think they've solved it. Genuinely, honestly, and completely.
These faculty complain about getting e-mail spam and sometimes even visits and phone calls out of the blue from people who claim to have solved it and want their proofs checked.