I wrote before about barter and how a barter exchange might work. I thought I'd give some thought to how the barter scrip could look. Please see my earlier post on barter if you haven't already.
Note that at the bottom of the note, there is a place where a barter exchange member can sign the note into existence. I probably should have put on there "not valid unless signed." Also be aware that this scrip may be illegal in the United States (or other countries for that matter). It may be legal if you modify it to be denominated in dollars, but you need to check all relevant laws for yourself.