Ring Lights are a must have if you want to take portraits or product shots. The unmistakable halo it leaves in the subjects eyes is a great effect and it's perfect at eliminating shadows. I own one and use it all the time, but you only get one colour: white, so why not build yourself one that offers 16.7 million colours?
Rob-24601 has posted a detail write up on SparkFun's Blog on how you can do just that. Consisting of a LuMini LED ring, SparkFun's LumiDrive LED Driver, some 3D printed parts, a bit of python code, a battery and some other various bits you can create some cool effects.
As you can see from a shot he took using his RGB Ring Light, you can create your own Warhol style effects without using any image editing software.
You can find a detailed write up here including a shopping list of all the parts you need and the STL files for printing the case. I have already ordered everything I need to build one and will document the build here on DIYHacker.