I2C is a wonderful interface. With four wires and only two GPIOs, you can connect a whole lot of sensors and devices – in parallel, at that! You will see I2C used basically everywhere, in every phone, ...

TI’s MSP430 chips are rather interesting – they’re low power, very capable, and available for under a dollar in most cases. Some of these chips, though, don’t have native SPI or I2C interfaces; ...