I'd like to use a central server to provide a common location for all of our mapping / imagery resources. Our data is primarily in the form of geotiffs with a variety of base layers from various sources on the web.
Geoserver, given a set of geotiffs, does a nice job of serving up tiles (via WMTS or TMS). However, I don't know of a way to easily proxy other external sources of data like the sample base layers from http://services.arcgisonline.com/ArcGIS/rest/services. Unfortunately, it doesn't seem like many services implement a WMS layer (or don't make it public). Currently we have logic in our application to special case various web services but it is a bit of hack. Ideally I'd like to present a common web services interface to all our tiling providers. This would enable WMS clients like world wind applications to "just work".
My only thought right now is to build a small python web service that would expose a list of capabilities via WMS and then add this service into geoserver as a cascading WMS store. This seems like a lot of work to simply serve up map tile URLs.
I am curious if this this problem has been solved before or if there is an easier solution.