I know it is possible to sent OpenURL requests to the WorldCat Registry service and have it chose a local OpenURL resolver based on what IP address you are coming from.
WorldCat OpenURL endpoint: http://worldcat.org/registry/gateway What I don't know is if WorldCat has an OpenURL resolver or can itself act as an endpoint for an OpenURL? I realize this is not the usual use case; normally an OpenURL would be searching against a knowledgebase of the holdings of a specific institution. With WorldCat, the OpenURL would have the holdings of all the constituent member libraries as its "knowledgebase". So, the purpose of this would be to discover where a given item represented by the OpenURL was held. A secondary purpose would be as a source of bibliographic citation information This could be quite useful discovery tool, especially for materials that are not widely held. Ditto the same question for OpenLibrary. Tom