Personally I hate PayPal because I always seem to have trouble with my credit card(s) and then get a lot of junk mail afterwards from PayPal.
Still I did manage to donate.
And will do so again.
Also PayPal seems so anonymous. Not sure why.
What I can't understand is why one of the ereader manufacturers does not distribute calibre with the device with a small library. Kind of like Nero with DVD writers. A licensing fee would perhaps provide a steady income for years.
While I like the personal feel of communicating with the calibre developer and his development team, and this might disapear if they became moderately wealthy
I think a living is not enough for such a great piece of software