I sent 2 photos, letter and SAE with US Stamps on to Zach on: 6th February 2012, and today I recieved both photos back, with only 1 signed, the other returned unsigned. Still very happy though.
address I used was:
Zach Galligan,
c/o Innovative Artists NY,
235, Park Avenue South,
10th Floor,
New York
NY 10003
USA