(For reference if you need help getting started: things I've made from Arduinos...
analog meter display for a bank for T1 network loads
cylon pumpkin (laugh, but eventually everyone makes one)
ambient light sensitive LED, using the same LED for sensing as making light
(pretty nifty trick, makes me wonder my more electronics
don't do it. No need for blinding indicators in a dark room)
2d ultrasonic anemometer
wireless network from ISM band ASK radios
(worked, but integrated solutions are probably better)
DC power controller/rationer for solar powered unmanned remote telemetry system
DC motor controller for http://8ball.lunarware.com
(not online yet)
Multichannel temperature monitor for a cranky air conditioner
(lots of data, no idea how to interpret, a lesson there somehwere)
Tiny LED xmas tree for my daughter,
red LED ornament blinks secret message in morse code
Multi channel servo controller from a PWM LED driver.
USB low speed interface with just a couple pins and resistors.
I've recently bought an arduino and have been playing around with it. I'm definitely a novice when it comes to electronics but I would love to know how that works.
Do you have writeups online for any of these projects?
The key points are remembering that there is capacitance on the pins of the microcontroller, and that while forcing an electron across from P to N emits a photon, absorbing a photon lets an electron back from N to P if it wants to go.
For quick prototypes using Ruby, check out RAD: http://rad.rubyforge.org/
I would also suggest browsing the rest of her site as it is a treasure trove of information related to electronics.
Making full RGB displays is pretty neat (and easy) to do with Arduino's pulse width modulation feature.
Well, at least everyone who's never heard of either Arduino or Google.