This tip just in from Blaine, owner of Blaine’s Color salon:

The “magic” fix…take 2 Bayer aspirin, crush them up in your hands, add shampoo to that and wash. The salicylic acid in the aspirin will counteract the alkalinity of the chlorine and remove the green almost immediately.

All over it, Blaine. Thanks!
photography by Patrick Demarchelier and stolen from Vanity Fair July 2008