ABiblestudent, the website that seems to me to strike the most appropriate tone for moderate witnesses is http://www.jwstruggle.com/. Seems to me like it's written from the perspective of Witnesses who have not given up on the faith, but know something is not right.
JWfacts.com was a tremendous resource for me, but only when I wanted to know the truth no matter how ugly it was. It may stir up some doubts in moderate witnesses, but it may also trigger the cult personality, IMHO.
I dont think a petition like that would raise doubt with a moderate because it's too directly oppositional to the group. It may work on someone who is more ready to exit.
Moderate JW's will probably open an email that appears to be coming from an elder, but if the writer doesn't thread very lightly it will trigger the aposta-radar. Pehaps an annonymous email that doesn't directly refer to religion per se, but has an empowering message.... (Not that one single email will do it, obviously, but it may start someone on the journey. Their self esteem has to be built up, and that takes more than one email.)
This is why I feel that those still in are in the best position to do this. It's about building rapport, giving support, offering unconditional love, and as Steve Hassan would say, empowering people to think for themselves.