The question came up in chat as to what Japan is or is not able to receive just yet in terms of aid. So as we get more information, why don't we post it here?
This New York Times discussion is the first mainstream news article I've seen on this topic:
Here's a link to a piece in The Nation detailing what organizations are sending aid; these could use financial support, although it's not clear that any gifts they receive will be earmarked (and I'm against earmarking, personally):
Maybe some Japan-specific relief funds will be established in the coming days and weeks. It seems like most of their problems, in terms of direct aid to survivors, are currently infrastructural and not related to money per se.