Discussion boards:
Beat The GMAT
The Beat The GMAT community is one of the web's largest resources for GMAT and MBA prep, featuring GMAT forums, GMAT scholarships, and free expert help for GMAT and MBA prep.
Studylink
This is StudyLink's MBA Worldwide site. A good source for sharing information with international students looking to study in the United States.
BusinessWeek Forums
BusinessWeek's business school channel provides a wide range of resources, including articles about business schools, interviews with admissions officers and business leaders with MBAs, and statistics about the schools. Within that channel are the BusinessWeek Forums, which are the most active forums available to MBA candidates.
Chicago GSB Discussion Forums
The University of Chicago's Graduate School of Business offers a discussion forum that is moderated by members of the admissions team and current students.
Wharton Student-2-Student
A popular forum for all business school applicants, not just Wharton applicants. Applicants can engage with each other, current Wharton students and members of the Wharton admissions committee.
Yale School of Management's discussion forums provide applicants with a forum to communicate with admissions staff and current students.
Rankings:
BusinessWeek
In addition to just rankings, there is great information on admissions requirements, the class profile (breakdown by ethnicity, age, test scores, country of origin) on a school-by-school basis.
USNews and World Report
The venerable ranking service's list is available on line, but to get any useful information you have to be a premium member.
Financial Times
Probably the most comprehensive list, as this includes all major international business schools. Has lots of useful information about each school, although the BusinessWeek list has more complete school-by-school information.