According to the WaP article, the database in question would be _required_ by the federal government... thus removing any voluntary aspect of it, so long as you want to fly on a plane. I have had the thought that it might be possible for an air cargo business to have as a stock benefit a guarantee that, for payment of any extra costs, any stockholder could ride on one of their planes. I don't know how the laws on the subject are worded, but I believe that a lot of restrictions are removed for planes other than standard passenger airlines. This might be a way to fly anonymously - Chaumian "is-a-stockholder" credidentials might be usable to arrange it (the local library's copy of Applied Cryptography is checked out, so I don't know for sure) anonymously. -Allen