A group here in Austin called the “bootstrap network” (with a rough mission to enable small companies and entrepeneurs to partner with eachother) is launching something they’re calling a “complimentary currency” system to facilitate and formalize this kind of business barter and “in kind” payment for services. And they’re using OpenID in some way to facilitate the whole system. Right now the scope is limited to Austin but it sounds like something that could easily be exported. Very cool and potentially revolutionary stuff.