The Student Representative Assembly of the MSU is the highest governing  body of the organization and handles a bulk of it's projects and efforts  for betterment of student life as well as the organization itself; most  of the work however is done through it's six standing committee's. 
Each committee will have one commissioner, four SRA members, and two at large MSU members/students elected to it.
So  hence those two MSU spots for each of the six main committee's as well  as spots for a number of other smaller/less active committee's are up  for Election this Sunday April 17th's SRA Meeting. The meeting starts at  12pm but the MSU elections won't be till a few hours in. 
For me  personally my greatest experiences and most productive work and  influence on student life at McMaster has come through committee's who  are essentially the workhorse of SRA and not through directly being an  SRA member.
For more information I would encourage everyone to check out: 
http://t.co/1XfzhiY
And also check out this blog post for more detailed info about these committee's 
http://php.orbiscommunicatio  ns.com/srablog/?p=283
This  is an excellent opportunity to get involved if you ever wanted to make a  difference at Mac or even if you were say planning to run for SRA but  didn't feel you have enough experience this year. 
Please feel free to ask questions, there is a couple of us SRA members active on MI!