This is indeed more focused on some of the ideas you liked most. But I think one lesson learned from Tipjoy is that merchant acquisition is the hard part about

This is indeed more focused on some of the ideas you liked most. But I think one lesson learned from Tipjoy is that merchant acquisition is the hard part about making a payments system. Increasing conversion rates is nice, lower overhead from micropayments is nice, but does is drive higher revenue? You have to prove that (or something else, like great customer service) to sell to merchants. I also think this focus on pay later doesn't necessarily work for those new to the system (i.e. everyone that matters) who could still be apprehensive and hesitant to commit to a transaction. The use of reputation isn't new. Spare Change had a system of reputation for those who reversed transactions. They let merchants block those with low reputations. A fun anecdote is that they needed to make a reverse-reverse transaction for those that wanted the reputation back. But let me bring it back to merchant acquisition. Amazon and Google are both having a hard time with this too. People don't want to spend development resources on a new payment processor unless they really, really need to. That's why solutions like http://wepay.com http://wepay.com are awesome, because they have a payment product designed for a sizable niche that really could use their services.