Could one set up a virtual remailer that floated around a set of news groups? The active remailer would pass an encrypted token to a randomly chosen member of the set which would become the remailer for the next interval. A compromized member of the set might then eat the token, rendering th remailer inoperative, but maybe that could be overcome. Although I don't have much more than a layman's grasp of cryptography my basic thought is to consider the set of potential mailers the way one would consider some known element in a cryptographic scheme, such as a randomly accessed lookup table, so that if a cracker couldn't determine the next element in the table, she couldn't determine where the remailer would be next, either.