Re: the discussion about an API and external tools, We have a bit of a problem in that we are using both the toolserver and the regular servers in ways they were not intended for. They are both really intended for Wikimedia-internal use. If we use them for external tools, Wikimedia does not directly benefit. If we were to have any great success, it would likely backfire and result in the thing being shut down or restricted.
So, do you think we should (sometime in the future, not tomorrow :)) consider approaching a chapter or outside org to donate hardware specifically for this purpose? Call it the Commons thumbcache server.
cheers Brianna