Daniel Pink summarizes an insightful article in the latest HBR on what really motivates workers.
Here is the main idea, which is interesting because it goes beyond simply saying that intrinsic motivation surpasses external motivation:
Amabile tracked the day-to-day activities and motivations of several hundred workers over a few years and found that their greatest motivation isn’t external incentives, but something different: Making progress (or what Drive calls “mastery” — the urge to get better and better at something that matters.)
So a key motivator is making progress. Good insight. Pink gives some more helpful quotes from the article in his post as well.
The article is a part of HBR’s “10 Breakthrough Ideas for 2010,” and I think you can obtain (purchase–sorry) it here.