In the afterglow of all the Christmas exchanges, the seed exchange from Heirloom Seed Swap guarantees you won't end up with some crazy sweater or a scale (seriously, someone brought scales to our exchange last night - and not a cool weigh-your-wheat one - an actual bathroom scale)
The Seed Swap site has some awesome post-apocalyptic goodies:
Red Russian Tobacco - you know that's going to be a major trade item for all the smokers who burned their last pack.
Heirloom Butternut Squash - the trader says this one grows well in the city - anytime you can pick up a hearty seed, it's a good idea
Apricots - I'm amazed at how quickly these grow and bear fruit
All the trades are FREE - pretty great resources too, and people looking for the seeds out of your garden.
You may not be able to trade the ugly sweater - maybe if you call it a survival sweater??