This is a very simple way to control a 3-phase AC installation in a delta configuration.
This circuit divides the voltage to three ranges: 12V DC, 9V DC and 5V DC.
It came with only an on/off switch. Adding an UNO to this LED chalkboard really gets your attention - it is quite a flashy pig.
Spectrum Analyzer using Zybo Z7 board, PMOD AD2 and Processing v3.x for displaying the spectral lines.
A virtual reality system using a similar device to Google Cardboard, a compatible phone and a lot of cables.
A generic setup for museum exhibit automation. DFRobot 4 relay shield 2.1 and screw shields, Hitachi 16*2 Display shield on UNO or Mega.
Connect your FPGA project to a wireless network and get information about your system while on the network.