well, i'm the cka for the chapter i initiated into, so i keep in constant contact with the collegiate chapter.
as for my alum sisters, i see most of them when the collegiate chapter has activities with the alumnae - and with the sisters i am closest with, i'll keep in contact via phone or emails.
also, myspace is a huge help in keeping contact with people, active and alum!!!
this last march was iota gamma's 5 anniversary, and the collegiate chapter put together a really nice event for us. they made sure that they contacted every sister that had initiated through iota gamma, to invite them. it was really nice!
i wish i was better at keeping in touch on a more personal level (like with letters and cards, not just e-cards and such) with more of my alumnae sisters, but it's so hard with people moving, working and having a life outside of the sorority.
i don't know if that really answers any of your questions, annice... but i wanted to reply since i didn't get a chance to before.