First three links to this post gets one of these postcards mailed to them:

D.B. (actually "Dan") Cooper was the man behind the only usolved air hijacking in U.S. history. Read more at the "wikipedia" link:

http://en.wikipedia.org/wiki/D.b._cooper

Quality of the postcards is the same as in the scan - not great. The back is a standard blank postcard mailing. If you want one sent without the addresses/stamps on the back, it will cost $1.50 in a bubble mailer.

First three links gets one.