More suggestions welcome.
Update: smofbabe has pointed me at ShelterBox, a Rotary-organised scheme to pack complete survival kits (tent, sleeping bags, cooking and eating equipment, torches, water tablets & carrier) for 10 people into boxes; the advantage being that you can ship them out very quickly as soon as you know there's a need anywhere in the world, and no special co-ordination is required at the other end other than getting them into the hands of homeless families. It's a British venture (with Canadian, US and Australian offshoots) and Gift Aid ready. You can't hypothecate donations, but they do tell you where the box that you contributed to went. They're sending 1500 boxes for Katrina relief.