Figuring out which particular organization to support is another challenge. As an example, I refuse to support any religious charitable organization because I believe that their assistance comes with the implicit understanding that the victims subscribe to (or at least condone) their particular interpretation of religion.

So, I tried to search for an organization which:

(1) Is not based in Pakistan (so I never have to transfer funds there).
(2) Is not affiliated with any religion (especially any of the extremist interpretations of Islam).
(3) Has a presence on the ground (so that they can carry out the work themselves rather than handing funds over to some other organization).

I have found MercyCorps to fit the bill. So, if you would like to assist the victims, please do so here: http://www.mercycorps.org/fundraising/pakistani_peace_builders