Web map tile caching system

 TileCache is an implementation of a WMS-C compliant server made available by
 MetaCarta. TileCache provides a Python-based WMS/TMS server, with pluggable
 caching mechanisms and rendering backends. In the simplest use case, TileCache
 requires only write access to a disk, the ability to run Python CGI scripts,
 and a WMS you want to be cached. With these resources, you can create your own
 local disk-based cache of any WMS server, and use the result in any WMS-C
 supporting client, like OpenLayers, or any TMS supporting client, like
 OpenLayers and worldKit.