I miss living with 14 of my best friends and seeing the others pretty much every day. I think that's the thing that's hardest to deal with about being alum. I only see some of my sisters once a year or so, which is really odd after seeing them every day for 3 years. But, I know that when I do see them, we fall right back to the way we were because of the special relationships we formed while in college.
Other than that, I'm an advisor, so I still get to go to meetings and rituals and all of that. I really haven't had the chance to miss those things!