TinyWire is an Arduino library, that provides I2C support for ATtiny micro controllers.
ATtiny micro controllers don't have built in support for I2C or SPI, instead they have only a Universal Serial Interface (USI). This library uses that to provide I2C support for ATtiny micro controllers.
To install the library, download or checkout the source code and place it inside your Arduino's libraries folder.
Check out the examples inside the /examples directory to find out how to use the library.
This library was originally written by Bro Hogan with contributions from rambo and svoisen