From Organic Design

A local exchange trading system (also local employment and trading system or local energy transfer system; abbreviated to LETS or LETSystem) is a locally initiated, democratically organised, not-for-profit community enterprise that provides a community information service and record transactions of members exchanging goods and services by using the currency of locally created LETS Credits.

WebLETS is an online transaction system for balancing "favors." The project was dead, but is now revived and the code is now maintained on Sourceforge by Terry MacKintosh, founder of Manasota LETS.

What is LETS?

From The LETSaholic Twist:

"LETS points are not dollars. They are more like favors. And when you can accept LETS points as being just "favors" from one member to another, you will not be concerned about the balances on their accounts; either in debit or credit... LETS account balances are just a record of how much each member is giving to, or receiving from, the LETS group. It is necessary to keep a record of each member's trading activity so they could strive to bring their balances back to zero, thereby keeping the system as fair as possible for all.
"By far, the biggest improvements ... in LETS groups have come about after members changed their concept of the group's purpose from that of being a local 'employment' or 'barter' system, to that of being a self-help group. Along with that comes a new understanding of what a LETS point really represents: changing it from being an alternative to cold, hard, 'cash' ... to a much warmer, favour. ..."
"It was easy for me to accept this attitude because my first contact with LETS members, at the NM LETS Get-Together, presented them in the same way. They were offering their services to me without any hint of obligating me to give back to them. "'

Since LETS is essentially a mutual giving network, perhaps the concept is most comparable to http://freecycle.org

See also