I recently came over a great presentation by Dan Pink who talks about motivation for people who have cognitively challenging work. He argues that businesses have relied too much on extrinsic incentives (money) instead of intrinsic incentives. He suggests that people should be given autonomy and allow the to work on purposeful task they can master instead of being promised large sums of money.
The topic is interesting and the speaker gives a very good presentation. So if you are interested in either incentives/motivations or giving presentations you should have a look at it.