idea: take email address as password, send periodic emails (on block solves and payment sent)
If, then please only optional + with unsubscribe feature (as this might be an easy way to spam people by subscribing them via this system to a mailing list)except we've finally invented the proof-of-work-to-spam system. You have to mine to spam them. And the spam isnt very interesting.
It'd be great if spammers joined the pool to spam out block solves and payment information, and contributed GH/s to the pool! not likely tho..
maybe "-- This payment info message brought to you by [1a|_iS!!!!"
lol.