As a general point, please put a license on your contributions if you put them on github. Don't much care what it is, and I don't mind paying, but don't make me do a song and dance to see what your price is.

Especially if you are already giving it away to open source projects -- my bet is most people who see "call me" as a clause will move on, even people you are actually trilled to help.

AGPLv3 would be a decent suggestion, but even your own license wouldn't be bad either.