The typical way of doing this is to use mechanical turk, there are some third party services (their name escapes me) which are built on top of mturk to provide reliability.
The typical way they do this is to have two different people enter the data and when there's a mismatch have a supervisor decide which is right.
The typical way they do this is to have two different people enter the data and when there's a mismatch have a supervisor decide which is right.