Economists since the times of Adam Smith (1723-1790), looking at non-specific pre-modern societies as examples, have used the inefficiency of barter to explain the emergence of money, of "the" economy, and hence of the discipline of economics itself. However, ethnographic studies have shown that no present or past society has used barter without any other medium of exchange or measurement, nor have anthropologists found evidence that money emerged from barter, instead finding that gift-giving (credit extended on a personal basis with an inter-personal balance maintained over the long term) was the most usual means of exchange of goods and services.
Check online swap markets and online auctions that have a bartering component such as Craigslist.com (check under "For Sale" for the Bartering category), Swapace.com, SwapThing.com, Barterquest.com, U-Exchange.com, Trashbank.com and Ourswaps.com. Check for local bartering clubs. Your local Chamber of Commerce may be able to provide you with information on similar clubs in your area.
A place to exchange your books with other members, Bookins says that they have “more available books than the largest Barnes & Noble.” Best of all, there are no membership charges or fees to speak of. Bookins arranges all the trades for its users, so members never have to contact each other at all to set up swaps. Sending items is free of charge, while receiving an item costs $4.49.
For $75 per year, Capital Bike Share gives members access to inexpensive bike rentals around the Washington, D.C. area. Bike stations filled with 1,100 bikes are located all over the district and nearby towns, and a single membership key grants you access to use and return any of them wherever you are. The first 30 minutes are free, and each additional half hour costs a few bucks. Members can also use the SpotCycle app for the iPhone, Blackberry, and Android device to locate the closest available bike. You can also try a limited plan, like a 30-day pass for $25.