I just finished reading Payoff: The Hidden Logic That Shapes Our Motivations, by Dan Ariely (Duke University).
It's about several work-based experiments done to determine how best to motivate employees. Many of the studies showed that money is not a good motivator in the long-term, and that recognition and the ability to view one's success/accomplishments can be far more powerful than a bonus check.
Quick read, it's a TED talk written down in book form, but worth taking a look. If anyone wants to borrow my copy, let me know and I'll bring it to the next member meeting.