At Amaze Entertainment I served as a Technical Artist writing tools and rigging characters (and other art tasks) for Spore Creatures for the Nintendo DS. I wrote a custom exporter to enhance the abilities of the Nintendo Nitro tools since there were several hundred parts and thousands of animations to export.
Here are flash movies of two of the many character rigs I created.
NITRObooster - lets you export thousands of models and/or scenes at a time
RigAssistant - a bunch of rigging and other character-related tools all in one handy panel
Renamer - part of the RigAssistant tool, lets you rename nodes with just one click
Vertex Color Panel - sets selected polygons to predefined vertex colors
Creature Face Keyer - lets animators sets face expressions by moving UV translations