Have each person go out and interview for another job once a year. Match their best offer if you think they're worth it, or don't and let them go be happy elsewhere.

This was basically what we did at Netflix, but since there were a lot of people not everyone had to interview. We had a pretty good idea of what everyone could get elsewhere and then we just paid them that much.

But we were all encouraged to interview elsewhere to learn our personal market and find out if there were other jobs out that that we would like more. It wasn't good for anyone to have you stick around doing a job you don't love.