Ask HN: Is there an alternative to PayPal for 'Donate' buttons?

I want to stick a 'donate' button on some of my open source projects. For reasons I imagine are obvious to most HN readers, I don't want to use PayPal. Keeping them running is enough work without having people's donations frozen and having to go through the "verification" process!

Are there any simple alternatives to PayPal's donate button for open source projects?

Thanks in advance!