Control your blinky!!!
Meet the RGBW LED Controller. It is a LED controller that features an embedded ATmega328 with an Arduino bootloader for easy programming, 4 channel LED control with dimming, 5 or 12 volt output, IR receiver, XBee header, RS-232 or TTL serial I/O, 2 push buttons, 12 pin extensions for all unused pins (6 analog and 6 digital), power and channel LED indicators, and dual power input options. You can control 5 or 12 volt LED’s via serial with adjustments to the level of any channel with ramping to the desired level, rate of ramping, color cycle start and stop, rate of color cycle, length of stay on each color during cycle. Fans and motors can also be driven with ease. Be sure and also visit the complete assembly tutorial! Power supplies, RGB and white LED strips, and XBee’s and XBee adapters are available at Adafruit!
I now have FTDI Adapters in the store, kit and fully assembled versions are available!
** Now shipping ver 2.2! Updates include an additional power input option, more pin options, thicker traces for more power handling, and some slight fixes/adjustments. **
I now have an updated downloadable PDF manual with pictures and linked index! 
Remember, this is not a shield, it works standalone, without an Arduino!
Please ask all questions in the forums, thanks!
If you are looking for one already assembled, in a case and ready to go, you can find a retail version at http://rs232ledcontroller.com.