Convertors
The items here in general will convert electrical signals from one kind to the other.
USB to Serial -- Connects to a PC and has drivers for all the popular operating systems. Serial output in 3.3V and 5V logic
USB to I2C -- Converts serial input from a PC to I2C signals
Voltage -- Combined 12V and 5V rectifier and regulator for use with just about any household wall power supply






