Servo twitching. I know, simple stuff, but it's interesting to play with on new hardware. Another Arduino example "sketch" (they got a number of these) called Sweep simply moves a servo through a set range, back and forth. Just looking at the sketch (listed at bottom) this timeshows a servo controlsignla connected to pin 9. They recommend using the boards 5 volts to power the servo, which is coming from the USB connection. If I'd had a bigger servo, or was under load, it might be appraoching the 500 mA USB limit (or is it more now?).