I'm a member of Order of Omega
We didn't do a lot of activities, though... we volunteered once at a food bank during my year and a half as an active member, and that was about it.
At my school, Omega tends to die back and then resurge - it seems to be popular with alternate class years. When I was initiated, with about 25 other people, there were only 4 collegiate members! A couple of years later, we all graduated, and they were back down to a handful of people...