Simplest PID example around!

Hi, i want to try out the PID library, but i dont think i got too much time/hardware to spare on that. I want to show it to some teachers to show them the arduino diecimila doing some PID so they start using it on some stuff.

So, i have an arduino, a breadboard, some leds, dc motors(but no drivers, one is very very very small, i guess i could plug it in directly), potenciometeres, a lm35(but no diodes to plug it in, dunno if theres another way to connect it)... so i wanted to know if you guys can imagine a easy pid example using this stuff or a very very simple one i can get with almost no hardware(its kinda hard to get shields, drivers or even basic electronics where i live =( )

I'm about to start using the little motor and use its own voltage for the retro to try to get the pid graph in processing... any ideas will be apreciated!

maybe you could add a light sensor (e.g. an LDR) to your list of parts. point a PID controlled LED at it, and have the LED compensate for changes in ambient light. room gets darker, led gets brighter. by adjusting the tunings you can control how quickly that happens.