Many larger cities have alumnae panhellenics that you could get in touch with. I'm sure if you go on the NPC website it'd list em somewhere
www.npcwomen.org
Since recs are references usually alum like to at least talk with the potential over the phone if not meet. I know I'd feel pretty bad if I gave a rec for someone I didn't know too well and she ended up not being a quality sister.
So yeah, get in touch with the alumnae panhellenics or even a phi sig alum chapter in your area(or your school's area)