Any cryptocurrency will do, but it obviously requires the customer be wired up to send you the transactions. I have several models kicking around in my head for

Any cryptocurrency will do, but it obviously requires the customer be wired up to send you the transactions. I have several models kicking around in my head for when we're going to need it. You may want to check out Bitcoin's microtransaction support. As you mention below, Ethereum may be a good candidate for this as well, given it can auto post transactions at a certain date.