Many of the projects I embark on or ponder constructing need some sort of electronic control. Mostly it's driving LED's but I still do a lot with motor control, servo interface, IR receiver, and PC comms. In the past, when in need, I'd throw together a perf-board circuit a little something like this. While an inefficient use of my time, it did provide a good learning platform and I didn't have the tools to do anything better. However, that has changed. Now, I will be using the e-unit PIC18F6622 breakout board. Thanks to the good people at Mentor Graphics, laying out this little gem was a breeze. I wanted to make a board that could serve as a stepping off point for any project I wanted to build. It's basically a bare bones design with pretty much all of the general I/O ported out to the header on the near side. Though I did include a few things that would make life easier like a RS232 level shifter, IR receiver and status LED's. Best thing about this board... it was free. Many printed circuit board manufacturers have first time buyer deals but Advaced Circuits has just about the best I've seen.
There are many types and makes of micro controllers out on the market but I like the Microchip PIC controllers because... well there are many reasons: good development tools, inexpensive, high performance, good community, etc. The PIC18F6622 is a good all around chip. It's got plenty of I/O, a couple of UART's, an I2C interface, on-chip A/D converters and it runs up to 40MHz. You're not going to do fancy signal processing on this but it does have enough smarts to handle a control system or two.
You may be asking yourself what I'm going to do with this board now that I have it. Funny you should ask, I already have something in mind. I have a few audio sources in my bedroom that run into the same amp and speaker setup. Currently I switch between them by manually depressing the appropriate button on an audio mixer. I'd love something that would autodetect what source is active and switch to that. A preamp volume control would be nice too. But that's another posting altogether.