My neighbors and I have been experimenting with spent coffee grounds, great for nitrogen and so on.
One neighbor in particular has been getting large amounts of spent grounds from Starbucks, you can call them in the morning and they'll give you a bunch instead of throwing it out. It comes with some filters mixed in, you can either weed through to pull them out - or, if you're composting, just throw them right in with the mix. Tea and tea bags are supposed to be fine too, but we haven't tried them yet.
After peak, coffee will probably be one of the more expensive items around, but I imagine there will always be at least some spent grounds available. Then again, that's what I once thought about used cooking oil too!
