Ask HN: Is there a way to automate the occasional micropayment?

I've been toying with an idea for an app which would occasionally make automatic donations to a charity.

I've been googling for a while, and it's not clear to me that there's an easy way to try this out (e.g. the paypal API).

Anyone know of a place to start? I'm looking for something lightweight to make a start prototyping.