Cacheability Engine

To help you understand how Web Caches will treat a Web page, the Cacheability Engine will look at a URL (and optionally any images or objects associated with it), giving both specific cache-related data about it, and a general commentary on how cacheable the object is.

http://www.mnot.net/cacheability/

Blender

Blender is a fabulous modeling and animating tool: it's an open source 3D content creation suite, and available for all major operating systems.

http://www.blender.org/