FreeLists: "...a service providing free, commercial-grade Internet mailing lists to all interested." No ads. There was a time when, if you came across a service like this, you'd think nothing of it (except, perhaps, cool). Now, you really have to ask what the catch is. And, if you're offering such a service, it would probably serve you to disclose exactly how you can manage to offer such a service and/or what your business angle is, if any, up front. (In the case of FreeLists, they explain why, but not how.)