Samaritan's Purse Wiki entry is interesting:
Samaritan's Purse
It's run by Billy Graham's son, and describes itself as an evangelical organisation. So definitely charity with at least one agenda behind it.
Quotes from 'Controversy' section:
"In 2003, Samaritan's Purse was widely criticized after its president, Franklin Graham, stated that Islam is a "very evil and wicked religion" "
"Residents from several villages stated they first had to sit through a half hour prayer meeting before receiving assistance."
"Franklin Graham has also been criticized in the United States, for drawing a full-time salary from Samaritan's Purse, while at the same time receiving a full-time salary from Billy Graham Evangelistic Association. Non-profit experts have doubted that one person can do two full-time jobs leading organizations that employ hundreds and spend hundreds of millions around the world."
My DCs school did the box thing last Christmas (although we didn't partake and gave money elsewhere). I thought about complaining at the time but didn't get round to it, although I will this year if it happens again.