For the edonkey hash (Message Digest 4):
http://search.cpan.org/author/OTAKA/...MD4-1.3/MD4.pm
I think it is a good idea, to put share the cracks through p2p networks. And since most cracks are rather small, it is fairly easy to keep them in the share for a while.
And after a few months (when the files are vanishing from ed2k) it should be nor problem to provide them by http (not to much traffic to be expected).
An extension: what about sharing a weekly (or monthly) collection of GCW patches? if the patches are bundled together in larger archives, they typically stand longer in the network, and it is easier to help with a reshare.