The Zilog is actually 3.3volts. You would use a simple regulator to provide 3.3volts from 12volts.
I use the Z8Encore and have had great success with it, the development kit is $39.99 and gives you everything you need to start programming the chips including a C compiler. I'm making a dash display and datalogging system with it, so, LED's but on the dash. I'm also using RC Servos to provide tach and speedo needle functions.
The AVR like Jem talked about and the PIC are much more popular microcontrollers, since the Z8e has just come out recently. Personaly I'm a fan of the AVR line as well. Both the PIC and the AVR have alot of support, so you might be better off going with one of those.
The learning curve is steep, especially if you have had no simple programming experince in the past, but it opens up alot of possibilities for you.