If you have a 3D printer then there is a good change it is running Marlin firmware. A completely open source project. Scott Lahteine is the main contributor to Marlin and has been doing amazing work on it.
Display this sticker as a badge of honor or to be really honorable display 200 of them.
You can also support Scott directly at www.thinkyhead.com/donate-to-marlin
Also check out http://marlinfw.org because even if you don't mess with your firmware you will find some great documentation of G-code and lots more to take your 3D printing to the next level.