Here is an excerpt from a great Drucker book I am reading:
Volunteers, we know, have to get more satisfaction from their work than paid employees, precisely because they do not get a paycheck. They need, above all, challenge. They need to know the organization's mission and to believe in it. They need continuous training. They need to see results.
It’s been apparent all along that money is never the sole factor to motivate a team. You need great people, challenging and exciting work, and above all, the ability to see the rewards at the end. This is easy to understand, but much harder to setup in an organization. In order to be successful at this it requires deep knowledge of the individual needs for each team member and the ability to provide these needs to the team as a whole. In the past year or so we’ve been become much closer to the ideal team in this sense. It all comes with great projects, experience, and a stable environment that attracts and retains top talent. At the same time we are far from perfect, but it is amazing when a team hits the that point where everyone jells together. You can literally feel the excitement and passion (even through IM and email :) )