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; ...
Several of the Mid-Range Enhanced Core PIC16 microcontroller devices have a Master Synchronous Serial Port (MSSP). The MSSP module can be used to implement either I2CTM or SPI communications protocol.