You can look at the work already going on in Japan through shelterbox here or look at their newsfeed/RSS here to find out how they are helping. You can also visit the page for their USA office here. This article details the arrival of the first set of boxes, each of which contains a tent, blankets, a took kit, and other items you can read more about here. If you're considering a donation, take a look and see how it will be put into action. It's one thing to give, but another to know how your giving will be used; this knowledge involves your heart even more than writing a check or entering a credit card number.