Here some useful links to search for datasheets:
The IC TC74 is a small temperature sensor that communicate over the I²C bus
Here a link to an USB to I²C bus tool, very cheap and great tool to test I²C communication.
The I²C interface program is very simple, yet very powerful and cheap compared to professional development tools.
Manual CNC controller for a proxxon MF70 milling machine, based on a 16F877 chip.
The IC MCP9808 is a small temperature sensor that communicate over the I²C bus, and is more accurate then the TC74.
Small example of sending infrared commands to TV and amplifier, written in C.