I'm looking for large, established barter networks with either a
Midwest or national scope. I already know of regional communities
through which people trade old cars for antiques or used guitars for
surfboards. I'm looking for a network where I can work with
businesses looking to barter business services in exchange for other
business services.

If the network doesn't have at least 500 members, it probably can't
help me. If the network is limited to a region that does not include
the Chicago metropolitan area, it probably can't help me.

An acceptable answer will list three networks, along with their
 size, contact information, and specific focus, if they have
one. A tip will be given for anyone who can find more than three
networks.

V