A few days ago, there was a really great post by someone who was developing a post apocalyptic setting. The idea started with a general list of items that might be found in such a setting, but then it moved to adding those tables to a list, and each time someone rolled on this list the item might be found, but it could never be found again. For a post apocalypse setting I think this is a great idea, it brings a level of scarcity to items. At first things are plentiful, then they get harder to find and maybe you have to move on to new areas once the old ones have been stripped clean.
I was so inspired by the idea that I started writing up tables of my own like this, but gave it my inevitable twist.
Instead of rolling a single d20 to determine what was found, roll two of them. Higher rolls indicate rarer items on these tables, so this translates to...If you choose the higher of the two rolls, you find the thing, but it is completely exhausted from the table, there was only a limited number of them (maybe even a single item)... If you choose the lower of the two die rolls, you find the thing and there are still more instances of this item out there to find. It doesn't quite consume the available resources as quickly as a single die, and the rarer/more-useful items will tend to disappear faster than the more-common/less-useful items.
I had examples of these tables to post, but with wet weather causing internet connection issues (and spending most of yesterday in hospital) I just haven't been able to upload anything.