Sift is a mobile app currently in development. It is an online trading platform that completely removes money from the equation. People are able to trade goods for goods, goods for services, and so on. The weird ivory sculpted salt shaker you bought for $5 at the garage sale might be worth 10 guitar lessons to Bobby, the guitar-playing salt shaker collector. 

The process is simple. You simply upload either an item that you are willing to trade, or a service that you are willing to offer. As you upload your stuff, you tag it with as many keywords as you'd like. If you're offering piano lessons, you would tag it with as many words related to teaching piano as you can think of. This will increase the odds of someone discovering you. You will be notified if somebody is interested in what you are offering, and from there, a conversation is started.