* C
- Check other uses of const (return value?)
- Flexarray? http://en.wikipedia.org/wiki/Sizeof

* AVR
- Take in account F_CPU everywhere CPU speed matters

* Functionality
  
* Circuit
- Look at oxygen sensor voltage with voltmeter/oscilloscope - is the voltage
  really so unstable?
- Put button and beeper pins in pins.h (watch out with OCR1A)
- AVCC should be connected to VCC via an LC network