The GunBot is basically a remote controlled gun and is a more difficult project as it involves both remote vision and control. Only a high level detail of the hardware & software is provided by that should be enough to get anyone started with a project similar to this one. Take care not to shoot anything that could be harmed!
This is a simple little project that shows how powerful automation can be. It uses ultrasonic sensors and a microcontroller to keep a spot light pointed at the object moving infront of the sensors. The project write-up has both detailed hardware schematics & the software.
The RGB combination door lock is a very intuitive thought for home security. It's tough to get passed a locked door if you have no clue how the security system works. The project write-up has a very detailed explanation with many visual aides.
This project might seem a bit ridiculous, but it could be helpful to someone out there in the world. Here is a portable password generator built with an AVR development board. It's a pretty quick and easy design so check it out.