Phillip Schuster built a handy little mult-tool for working on hardware.
This neat little gadget can do things like generate PWM or DAC signals, read serial output of your microcontroller project, as well as several other useful functions. The design of the Little Helper was inspired by the iPod interface. It’s custom touch wheel allows for fast one-handed operation.
The project is open source. You can find the code on Github.
There is some additional discussion of the project on HackADay.