It is fairly common knowledge that one can continuously use active birth control pills in order to stop having periods (under the supervision of a gynecologist). Then Seasonale came along, which shortened the menstrual cycle down to four planned periods a year. Now a new pill, Lybrel, promises to do away with periods all together.
It is safely being used in Europe and in clinical trials is as safe as regular birth control pills. But its FDA approval has been postponed, although the company is positive it will get approved within the next year.
If you want to suspend your periods, for whatever reason, talk to your gynecologist. According to Allure October 2006 (p. 208), The American College of Obstetricians and Gynecologists reports that 53% of female ob-gyns use birth control pills to skip their own periods.