Graduate Management Admissions Council - Official test registration and information on MBA financing and programs.

The Delta Course - Online GMAT study course, test debriefings, and advice on stress. Practice test with immediate feedback. [Requires subscription]. Offers daily GMAT practice questions by e-mail.

GMAT Buster - News and information, free practice questions, tests and preparation resources.

Manhattan Review - Preparation courses in Germany, and MBA admissions consulting.