This may be old news to many, but it's my current interest.  The
microcontroller chips cost as little as $2 on ebay.

-- excerpt --
Many people would like to get started with microcontrollers, but don't
know how to begin. That's what this page is all about -- how to get
started. With a microcontroller you can do things that would be
difficult to do with discrete logic. Besides its power, you can easily
"change your mind" with a microcontroller -- something you can't do with
discrete logic.

The PIC isn't for every project. It won't replace a PC, or even a larger
processor. But for many jobs it is just the right size, inexpensive, and
doesn't require much in the way of support hardware.

What are some things people have done with a PIC?

 Morse code keyers 
 Robots 
 Data logging instruments 
 Phone dialers 
 Clocks and timers 
 Much, much more 

http://tutor.al-williams.com/pic-intro.html