New to microcontrollers...options for getting up and going cheaply
AVR is one of the big ones these days, especially with the popularity of the Arduino platform.

The IDE itself is free, and ISP programmers can be had for as cheap as $2 (if you're willing to wait a bit). You can either use a full Arduino (or compatible) board, or you can use bare AVR ICs on a breadboard, either with one of the Arduino bootloaders (for direct programming) if it's large enough, or one of the aforementioned programmers.