MSP430 + ShiftBrite
I like the Texas Instrument MSP430 microcontroller. It’s cheap, low-powered and has tons of features. You can get a complete development board, with embedded debugger, software and 2 controllers for $4.30!
I also like the macetech ShiftBrite RGB LED modules. Makes it easy to add a bit of color to electronics projects.
So here’s a library that makes it easy to control a ShiftBrite from an MSP430: