Have you ever wanted to make your remote-controlled car run by itself? Nico and Others (dubbed, 'Team YoungerWoods') have done it! :)
A robot which measures the user's body temperature, decides 'happy' or 'sad', and draws either a smiley or frowny face.
Build a car hacking spy device to remotely read and send CAN commands and track GPS location. All based on open source software/hardware.
The control of a robot may be painful as you have to develop specific clients for each mobile device. I propose a Web based control