I was searching on yuotube for arduino projects in Portuguese and I found a very explanatory video (https://www.youtube.com/watch?v=xQj-ur8k73Y&feature=related) using an arduino, a relay, a transistor and a light bulb. This video is part of a website called āLaboratorio de Garagemā which means garage laboratory, if you havenāt guessed yet. It is a website and a blog full of tutorials and projects using different kinds of electronics, most of them with arduino. There is a discussion board where you can ask questions and also suggest new projects.
I found this three video projects that I liked it. Two of the projects are with a remote controlled car with a camera on top of it, that shows where the car is going, and the other one uses a touch screen that activates different leds as you touch it.
http://labdegaragem.com/profiles/blogs/robo-controlado-pela-internet-arduino-codename-rafinho
http://labdegaragem.com/profiles/blogs/robo-wifi-controlado-via
http://labdegaragem.com/profiles/blogs/projeto-com-nintendo-ds-touch-screen-e-arduino
