I feel like a few companies have tried this over the years.. The concept of a tip jar that you'd fund and then be able to disburse on participating websites.

I feel like a few companies have tried this over the years.. The concept of a tip jar that you'd fund and then be able to disburse on participating websites. Then payments could just be aggregated and paid out periodically from the tip jar provider to the publisher.. But you need some kind of critical mass for this (both users and publishers), and I don't think anyone has cracked this yet..