Many things have been used as money throughout human history: sea shells, cows, metals, cigarettes, even things with no inherent value (think: little pieces of paper). Thanks to a link from Doc Searls, I've just been reminded of the local currencies movement, which seeks to replace government money with grass-roots scrip generated through voluntary exchange in local communities. The example I'm most familiar with is Ithaca Hours in the area around Ithaca, New York. Ithaca Hours are an example of time dollars (a similar project seems to be starting up just north of me in Fort Collins, Colorado). Interestingly, these projects all seem to come from the cultural or political left, and tend to put the emphasis on "small is beautiful" themes like healthy communities and even protecting the Earth rather than the traditional rhetoric of stable money and objective value that one associates with prominent and not-so-prominent advocates of a return to the gold standard. Open money, anyone? (Yet another example of when "open source" means free in the sense of speech, not beer.)
Think globally, mint locally. :-)