I sent a LOR, sae, $5 US to cover return postage and an 8x10 to Clark Gregg using the 3 Arts address that was in the database. I cant remember the exact date I sent (I think it was march 2014), but I recieved my picture and the dollars back signed on 02/08/2014:
http://dnorth92.wordpress.com/autographs-2/clark-gregg/
Comments on authenticity welcome!