My experience has been the same. I donated $50 to Cyanogenmod a couple of years ago (FFS, they saved my buying a new phone!) and got a delighted email from Steve Kondik.
I used to assume the FOSS world would be supported like the Linux kernel is, but now I realize that many cool projects need a user-funded model. I choose a project to donate to weekly, as well as supporting gittip.com. It's not much (and I hope to increase it markedly one day), but I want to live in a world where Free hackers can just hack, and not stress about money.
BTW I've never used GNU LilyPond, but I'm delighted such a thing thrives. Do you take BTC?