I've been working with Seeed Studio for the last few months to prototype an Arduino-compatible shield that highlights the TLC5490 driver chips and used three of them to drive a 4x4 RGB LED matrix. This was based on a circuit we built at the first HTINK workshop here in New York City.
Now, Seeed has put together full kits that have everything you need to build the shield for yourself for $35. They also have the bare PC board for $6.50 too if you already have the parts or want to source them yourself.
I've documented the project at http://combee.net/rgbshield. I need to put some actual code examples there... right now, they're scattered around the net a bit. On the shield, each TLC5490 chip is used to drive one of the color channels, so you can adjust the current-limiting resistors to get a better color balance.
This wouldn't have been possible without the excellent TLC5490 library at http://code.google.com/p/tlc5940arduino/. We used that as the basis for our sketches at the workshop. I'm about the update the RGB shield page with some code samples and instructions on using the library.