I've been thinking more an=bout my PID motor controllers based on the ATtiny13, and have determined that I must be crazy. I did some googling, and everyone else that is making a motor controller using an AVR is using something like an ATmega168, an ATmega32, or other large controller (almost always a mega). The application note on Atmel's website (look for AVR221) doesn't recommend a certain controller at all. So am I crazy to try to shove this all into an tiny13? We'll see how it goes.
I went over to AVRfreaks.net to see if there is anything larger than the tiny13 that has the same pinout. It looks like I can use the ATtiny25, ATtiny45, or ATtiny85 for 2, 4, or 8kb of Flash space. Too bad I already bought a dozen tiny13 chips.