The SDM program has numerous committees. Their purpose is to make the students feel involved in the program, like the students at least partially "own" the program. During the first week of the January program, the SDM staff will provide an introduction to the committees and ask you to volunteer for at least one.
All the committees have a purpose. Figure out as early as possible how they have been running and do your best to contribute. Set up conference calls and Sloanspace folders to suit the needs of your year. Arrange for one person from each committee to be on the SDM Council to keep them all aligned. If you are on one of the committees that are joint with LFM remember that you are an ambassador for SDM amongst the very best students at MIT: they are a demanding bunch who are both pampered and workaholics.
Some committees have far less work than others, or so it may seem. But try to help out...