One Percent for Open Source
ericholscher.com
ericholscher.com
I'm not a fan of this. If I release an open source library, I am under no obligation to continue development or support it. I'd happily take the donations, but there is absolutely no moral or ethical reason I'd feel compelled to maintain the project.
If I do something I'd rather get paid or not at all and I've chosen that, rather than cap out looking for tips.