CS50 Seminar: Arduino
Although working on software is fun, I've always been inclined to work on hardware projects. They just incorporate many more types of skills: programming, circuit design, and creativity!
I did not start off with Arduino earlier, but after learning the basics through Jeremy Blum's Exploring Arduino, I felt that I really expanded my toolkit. In my seminar, I go through getting started with Arduino, a few basic projects that people could build up upon, and debugging techniques.