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.
Trade did occur in non-monetary societies, but not among fellow villagers. Instead, it was used almost exclusively with strangers, or even enemies, where it was often accompanied by complex rituals involving trade, dance, feasting, mock fighting, or sex—and sometimes all of them intertwined. Take the indigenous Gunwinggu people of Australia, as observed by the anthropologist Ronald Berndt in the 1940s:

Make the deal. After you've found a barter partner, get the agreement in writing. Make sure you detail what services or goods will be involved, the date of the exchange (or work to be done) and any recourse if either party reneges on their part of the deal. If you are working through a membership-based bartering association, they will likely provide all the structure and paperwork you need for the deal.

Bartering allows individuals to trade items that they already have but are not using for items that they need while keeping their cash on hand for expenses that cannot be paid through bartering such as a mortgage, medical bills and utilities. Bartering can also have a psychological benefit because it can create a deeper personal relationship between trading partners than a typical monetized transaction. Bartering can also help people build professional networks and market their businesses.
Can you teach a skill like canning or cooking from scratch?  Food staples will be more readily available than the processed food many are used to buying at the grocery store and fast food.  And although many in the preparedness community know how to can and cook from scratch, your common everyday American doesn’t.  They wouldn’t know what to do with flour, eggs, and a little oil.
It’s hard to answer that without actually seeing a modern gift economy in action. Luckily, modern gift economies actually do exist. On a small scale, they exist among friends, who might lend each other a vacuum or a cup of flour. There’s even an example of a gift economy on a much larger scale, albeit one that’s not always in operation: The Rainbow Gathering, an annual festival in which about 10,000 people gather for a month in the woods (it rotates among various national forests around the country each year) and agree not to bring any money. Groups of attendees set up “kitchens,” in which they prepare and serve food for thousands of people every day, all for free. Classical economists might guess that people would take advantage of such a system, but, sure enough, everyone is fed, and the people who don’t cook play music, set up trails, teach classes, gather firewood, and perform in plays, among other things.
The Buy-day (Wheat) Ecological Life Associate summarizes a vision of life in Gezi as follows: "In our world, which is being poisoned and destroyed by consumer culture, we need sustainable and self-operating models of lifestyles, including a barter economy, ecological food production, arts and craftsmanship based on needs, renewable and effective energy use, agricultural models backed by society, permaculture, slow cities, transitional towns, eco-villages, district gardens and secondhand and recycling systems.

An online swap meet of sorts, at Swap.com there is no bidding or money exchanged. Rather, you offer to trade the stuff you no longer want. You’ll then have the ability to choose from books, movies, CDs, and other items. The site doesn’t seem to have monthly charges, but you’ll be responsible for shipping costs associated with items you sell. Swap has its own free iPhone app for simple listing and searching.
Many prepper fiction novels eventually get to a point where there is a barter economy or the characters visit a Trading Post.  For instance, a trading post plays a prominent role in Mark Goodwin’s series, Seven Cows, Ugly and Gaunt: A Post-Apocalyptic Saga of America’s Worst Nightmare.  In the novel, the characters use silver to purchase the necessary items to survive and make life easier.  Goodwin’s novel is a post-apocalyptic EMP story.  The poop has really hit the fan in this one!
And, if you’ve been in the Preparedness community for any amount of time, you are familiar with Fernando “Ferfal” Aguirre.  He wrote about his experiences of the economic collapse in Argentina in his very popular book,  The Modern Survival Manual: Surviving the Economic Collapse.  Argentina hasn’t really recovered from their collapse many years ago.  This video discusses one Barter Market Club that is located in an abandoned textile factory.
And that means everything from tuna to stamps to cigarettes has its own unique value in a trade and barter market. — Alexandra Cardinale, Vox, "Why ramen is so valuable in prison," 14 Nov. 2018 European officials were also looking at a barter system that would allow Iran to sell oil, for example to China, and use the proceeds from that sale to purchase goods or technology from Europe. — Laurence Norman, WSJ, "Europe’s Payment Channel to Salvage Iran Deal Faces Limits," 25 Sep. 2018 With unemployment around 9 percent and consumer prices surging, some Argentines are again turning to barter clubs, which first emerged during the collapse nearly two decades ago. — Almudena Calatrava, Fox News, "Argentines seek soup kitchens, barter markets amid crisis," 10 Sep. 2018 This particular search insired Gellar and Laibow to hop on the phone and barter. — Colleen Leahey Mckeegan, Marie Claire, "Sarah Michelle Gellar's Second Act? Disrupting the Food Industry," 18 Apr. 2017 Choco Pies became so prevalent for sale or barter on the streets that North Korea reportedly banned their import to Kaesong in 2014. — Brian Murphy, Washington Post, "The Choco Pie dividend: South Korean firms are drooling at the prospect of business in the North," 17 June 2018 In 1996, amid crippling famine, Ji tried to steal a few pieces of coal from a rail yard to barter for food. — Brian Murphy, BostonGlobe.com, "Could these outspoken North Korean defectors return home?," 11 June 2018 In 1996, amid crippling famine, Ji tried to steal a few pieces of coal from a rail yard to barter for food. — Brian Murphy, BostonGlobe.com, "Could these outspoken North Korean defectors return home?," 11 June 2018 Instead, like many early civilizations, they were thought to mostly barter, trading items such as tobacco, maize, and clothing. — Joshua Rapp Learn, Science | AAAS, "The Maya civilization used chocolate as money," 27 June 2018

Michael Linton originated the term "local exchange trading system" (LETS) in 1983 and for a time ran the Comox Valley LETSystems in Courtenay, British Columbia.[26] LETS networks use interest-free local credit so direct swaps do not need to be made. For instance, a member may earn credit by doing childcare for one person and spend it later on carpentry with another person in the same network. In LETS, unlike other local currencies, no scrip is issued, but rather transactions are recorded in a central location open to all members. As credit is issued by the network members, for the benefit of the members themselves, LETS are considered mutual credit systems.

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