The organization behind the GMAT is the GMAC. Their website is www.mba.com, a useful website to learn about all GMAC activities in both past and future.
The GMAC was founded in 1953 by 9 business schools. The goal was to create a uniform method of selecting the best students among many applicants: the GMAT test. The predictive validity of the GMAT test has led to great successes, to be seen as growth in both the number of schools accepting the exam as a method of selection, and the growth in the number of test takers.
The GMAC is a non-profit organization that is involved in many aspects of business school life, next to the GMAT. Among other things, the GMAC provides partner organizations with volume trends, geographic trends, GMAT candidate profiles, and survey results obtained from corporate recruiters surverys, management edcucation graduates surveys, prospective students surveys, and alumni surveys.
All in all this makes the GMAC a very big organization in worldwide management education. This is also shown by numerous grants given to students around the world, and volunteering both time and money to initiatives improving management education.