Other Examples of currency

Although these are not examples of trade I found two other interesting travel stories.

Trade / gift giving
Keiichi Iwasaki leaves Japan to bike around the world with only $2 and has made it to 37 different countries he was able to make money along the way by accepting tips for performing magic tricks in the streets.
http://www.theplaidzebra.com/man-leaves-japan-to-bike-around-the-world-with-only-2-and-has-made-it-to-37-different-countries/

Currency
Felix Weis traveled the world using only Bitcoin as his form of currency.
These were his rules

1. No banks. And that meant no Western Union, no money exchanges, no converting USD to euros, no euros to yen. 
2. Bitcoin first. He had to use Bitcoin whenever possible.
3. Cash only for bitcoin. Recognizing that there would be times when he would need local currency, he allowed himself to do peer-to-peer exchanges of bitcoin for cash. And that led to some fun adventures.

http://www.forbes.com/sites/laurashin/2016/07/14/this-man-traveled-around-the-world-for-18-months-spending-only-bitcoin/#2409d5e261ea