s3d is an XML schema for 3d scenes, objects, and so forth (intended primarily but not exclusively for computer games). The problem is that often as a games developer you need to work with many 3d editing tools and rendering engines, and there should be an easy and portable way to move objects, levels, etc. around. By having a common intermediate file format, you only need to write one exporter per tool and one importer per graphics engine. Also, you can develop generic tools which are not tied to any particular engine.
ScenePainter is a program for creating comics by (re-)arranging prefabricated graphic elements, taken from a media library. It can also be used as a developer tool for programmers and artists that are building games using threering's nenya library. Currently, ScenePainter does not ship with resourcefiles of its own, but is able to extract graphics from the games "Puzzle Pirates" and "Bang Howdy" by three rings design, inc. These graphics however, are copyrigthed materials and require permission to be used (e.g. for creating fan art).