Here's some information I received from PrincetonReview.com about accelerated MBA programs (and several of these are online MBA programs):
Accelerated graduate business programs take less than the traditional 2 years to complete. If you majored in a business-related field, you can often complete an accelerated MBA program in as little as 12 months. Even if you've never studied business, many programs can be completed in just 18 months of full-time study or 24 months of part-time study.
Colorado State University (Online)
21-month MBA from a top research university
Ranked a #1 Best Administered program by The Princeton Review, CSU offers an Online / Distance MBA that has been AACSB-accredited for over 30 years. The program can be completed in as little as 21 months. CSU hosts Centers of Research Excellence in: Global Business, Social Marketing & Social Issues, Entrepreneurship, e-Business, and Real Estate.
Willamette University (Salem, OR)
21-Month Full-Time MBA
Willamette University's full-time MBA program has been profiled as one of the country's best business programs by BusinessWeek, U.S. News & World Report, and The Princeton Review. Willamette is a national leader in early career MBA education and prepares students for their first professional position, career change or advancement. Specialized areas of study include: Entrepreneurship, Marketing, Global Management and more.