I love what W&L's Panhellenic did. There was one group at my school that had recruitment violations 2 years in a row. Both times, Panhellenic took away their right to do songs or chants during entrances on Skit Night. It was very noticeable and a negative for PNMs. The other chapters were instructed NOT to discuss or answer questions about it from PNMs (we had to respond with "Oh, I don't know" or something, I can't remember exactly what the given response was), but the Rho Chis could explain the situation to the PNMs. Of course this would only work at a school where door chants are a significant thing, but I think it was fairly effective with this group... or maybe not, since they had violations 2 years in a row. hm. Well, anyway, all the other groups were very satisfied with the resolution - I guess we were sadists. LOL.
ETA: Ah yeah. What APhiAnna said!