On Why We FLOSS

The results of a very interesting study [PDF link] are a good insight into why people contribute to Open Source software projects and in some ways, it can be extended to other Open Source movements, Wikipedia et. al.

If you're a FOSS contributor, you're about 30 y.o. almost exclusively male (sic) from North America or Western Europe, with 12 years of programming experience and spending about 10h/week on 2 or 3 FLOSS projects. You feel strongly that the hacker community is the primary source of your identity.

You're either self-taught (40%) of have been formally IT trained (51%).
There are good chances (40%) that you're paid while contributing.Your primary motivation lies in your ability to express your creativity; You belong to one of the following 4 clusters (names are MTG's not that of the study), identified along your secondary motivations:

[ 25% ] The Professional: (86% are paid) You need FLOSS for work-related issues
[ 27% ] The Hobbyist: You need FLOSS for non-work related issues
[ 29% ] The Intellectual: You like to improve your skills and need/like intellectual stimulations
[ 19% ] The Altruist: You like to give to the community and believe code should be free/open

Contrary to the mainstream sociological belief, extrinsic rewards (money) does not decrease your intrinsic motivation (here your feeling of creativity).