I want to share my experiences as a newbie with GNU-GCC for AVR. I looked hard for simple, generic, complete and documented I2C bitbang code for any AVR, but couldn't find this anywhere. My application is intended to be a hardware+software building block which can be integrated into any larger project/product. It's not terribly technologically elegant, but is very straight-forward and doesn't use the AVR TWI advanced function hardware. Any two pins on any one port can be used for SCLK and SDA (ACK*). No hardware timers are used - only software ones.
Any hardcopy of this code "is suitable for framing or wrapping fish".