I think sites like that one are great ideas, but I must admit in my 8 years of service I've never actually seen one of the "Thank you" notes.
Where do they go?
I must tell you this though, while I was stationed in South Korea and Kuwait I received dozens of "Thank you" letters by mail...very touching, a lot of them were from grade school children. Some folks even sent me boxes of goodies for Christmas.
I truly appreciate your support...
Sergeant Martoch
USAF