I have seen a number of mentions for using the TLC5940 to control motors but didn't see any actual projects. I am working on a robot that will drive many small motors so this seemed like a good way to get a large number of pins to control DC motors for a very reasonable price. (depending on your h-bridge and motor size of course.)
Here is the schematic showing a TLC5940NT controlling a single motor through a L293B H-Bridge using an external power supply.
My blog post for this project is here: http://rpgduino.wordpress.com/2010/04/09/to-build-a-robot-part-4/
Please let me know if you see any problems with my design or schematic.