The point of my contests is to encourage people to write useful tutorials that can help others make robots of their own. It really doesn't matter to me what you make, as long as your tutorial can convey tons of useful robotics related knowledge to others.
other examples of things valid for the contest:
invent a new sensor
connect a playstation controller to a microcontroller
kalman filter tutorial
make a lithium battery charger
voice recognition for microcontrollers
You can make the most awesome beer drinking robot ever, but if your tutorial doesn't show how, you won't win
(hoping that answered your question)