While some people may balk at an online community for finding babysitters, I know several parents who say it’s actually very difficult to find a sitter they can trust. BabysitterExchange started in 2000 as a babysitting co-op, and it has since expanded to the point that members use it to reserve time when they just have some errands run, need help tutoring their kids, or want a temporary house-sitter.
PaperBack Swap is exactly what it sounds like: a place to swap paperback books. Currently, more than half a billion books are available for trade on the site. Just list the books you don’t want anymore and other members will find them. When someone requests one of your books, you just mail it out and then choose any available book that you want to receive. Swapping is easy, and membership is free.

An online community in which you can either share free stuff or rent items for a fee, NeighborhoodGoods bills itself as a “social inventory,” enabling members to save money and resources by borrowing what they need to use. While joining is free of charge, you can create private sharing groups for your business or neighborhood for a small fee: $36 for six months. 

At least at for my children, all of the little league sports are sponsored by different local businesses. They usually pay the cost of uniforms and donate a certain amount of snacks and such. In return, they get their company name on the jersey. The school often have fundraiser auctions and things, too, that are sponsored by the booster club. A lot of places donate laptops or other items in exchange for them mentioning that their company donated the product. 

Then again, it’s one thing to keep a community alive and well when everyone’s camping in a forest and they’ve all opted in to that vision. It’s quite another to imagine a gift economy enabling humans to build skyscrapers, invent iPhones, put air conditioners in every house, and explore space. (The same goes for collecting taxes and running large businesses.) Not that it’s an all-or-nothing situation: We already have gift economies among friends and family. Perhaps expanding that within small communities is possible; it’s certainly desirable.
Barter exchanges have their own unit of exchange, usually known as barter or trade dollars.  Trade dollars or barter dollars are valued in U.S. currency for the purposes of information returns.   Trade dollars allow barter to take place between parties when one party may not have a simultaneous need or desire for the goods or services of the other members.  Barter exchanges act as the bookkeeper for keeping track of trade dollars that participants accumulate. Earning trade or barter dollars through a barter exchange is considered taxable income, just as if your product or service was sold for cash.
In recent years, barter has enjoyed a resurgence as a means of countering economic insecurity, unemployment and worker exploitation. The nature of modern-day work, the pervasiveness of the Internet and the rise of social networking have all contributed to its spread. Other examples of alternative economic systems include gift economies, sharing economies and time banks.
Whether or not one agrees with such broad claims, it’s worth noting that monetary debt, a byproduct of currency, has regularly been used to by some groups to manipulate others. Thomas Jefferson, for instance, suggested that the government encourage Native Americans to purchase goods on credit so they’d fall into debt and be forced to sell their lands. Today, black neighborhoods are disproportionately plagued by debt-collection lawsuits. Even after taking income into account, debt collection suits are twice as common in black neighborhoods as in white ones. $34 million was seized from residents of St. Louis’ mostly black neighborhoods in suits filed between 2008 and 2012, much of which was seized from debtors’ paychecks. In Jennings, a St. Louis suburb, there was one suit for every four residents during those years.
Companies may want to barter their products for other products because they do not have the credit or cash to buy those goods. It is an efficient way to trade because the risks of foreign exchange are eliminated. The most common contemporary example of business-to-business barter transactions is an exchange of advertising time or space; it is typical for smaller firms to trade the rights to advertise on each others' business spaces. Bartering also occurs among companies and individuals. For example, an accounting firm can provide an accounting report for an electrician in exchange for having its offices rewired by the electrician.

When two people each have items the other wants, both people can determine the values of the items and provide the amount that results in an optimal allocation of resources. Therefore, if an individual has 20 pounds of rice that he values at $10, he can exchange it with another individual who needs rice and who has something that the individual wants that's valued at $10. A person can also exchange an item for something that the individual does not need because there is a ready market to dispose of that item.