Personally, all orgs/groups I joined (or am considering joining) post-DST initiation were not because of a void left by Delta. For the most part, I was asked to join said groups because of the leadership and committment I've shown to Delta. In reference to those that I joined on my own (as in it was my initial idea, not as result of a suggestion/nomination/outside encouragement), I did so because I felt that my experience within Delta would be benefit that org, or because, as Summerchild stated, it highly complemented another personal interest.
ETA: Which is not to say that DST does not have some sort of small group of Sorors with the same "other" interest. Delta is about scholarship, service and sisterhood - things that I engaged in pre-DST, support through DST, and outside of DST. If I limit all those interactions to just within Delta, I'm gravely robbing my community of the gift that is me.
