Hi,
I think I read somewhere that someone mentioning Flattr. However, the amount that can be donated is pretty limited. Another thing I just got to know about Flattr is that they have an ?offline? version called ?Flattirl?. It generates a QR code that you can use at venues, etc., and people just have to flash your barcode to access the ?Flattr? button and donate.
I don?t know if it might help you in some way. Good luck.