I love the Arduino -- it makes hardware hacking easy enough even for a hardware klutz like me. I blog most of my Arduino projects: see the Arduino tag on Shallow Thoughts.
You can get source code for most of my Arduino hacks in my GitHub Arduino repository. There's a little more description of some of the older projects at Akkana's Arduino hacks.
I gave a presentation at the 2012 SCALE10x,
with Linux and Devices.
There's a video of the talk at that link as well as the description.
Or view the slides from the talk here:
Fun with Linux and Devices: slides.
Advance to the next slide with spacebar, Page Down or Right arrow.
A list of useful links and tips from the presentation: Cheatsheet: Fun with Linux and Devices.
I give a one-day workshop on Robots and Sensors at the GetSET science and technology summer camp for high school girls. 2012 was its first year, and I'm looking forward to the 2013 workshop.
I build my Arduino software on the commandline with make, not inside the Arduino IDE: you can read about how that works at Command-line Arduino development.
I hope I inspire some people to have as much fun with Arduinos as I've been having!