One of my wife's friends is a volunteer with a local charity, and at this year's party one 'at the time my wife thought terminally' ill young boy (age approximately 9 or 10)was asked by Santa if he wanted anything besides the R/C truck. He said, 'yes, I would like christmas cards from all over the US (& elsewhere if you're so inclined -Ned).
I'd rather not publish the address just in case some weirdo trolls through google etc... so if you'd like to help, drop me a PM and I'll send you the address.
*note, he is NOT terminally ill. He Is in treatment and is in remission