I believe, at this time, almost all NPC sororities offer some form of it, except for Kappa Kappa Gamma and Alpha Epsilon Phi (and possibly SDT and Theta Phi Alpha -- I don't know anything about their alum initiate policies). However, Kappa is working a program to implement it in the future . . . I am not sure if AEPhi is or not. Still, each sorority has different standards for who they will allow to become an alumnae initiate -- some will ONLY initiate women who have done a lot of good for the sorority, such as a member's mother who's done years of charity work for her daughter's chapter, things like that. Others will initiate any woman who seems to be a good addition to the sorority but didn't have the chance to go Greek in college.
DG, Alpha Phi, Gamma Phi Beta and AOPi seem to be popular choices for alum initiates, at least those on this board; I am not sure if there is any reason for this or not.
See CutiePie2000's GREAT thread on this subject here:
http://greekchat.com/gcforums/showth...threadid=20287