Microchip MCP3008-I/P 8 Channel 10-Bit A/D Converter with SPI
The Microchip Technology Inc. MCP3008 is a successive approximation 10-bit Analog-to-Digital (A/D) Converter with on-board sample and hold circuitry.
A great accompaniment to the Raspberry Pi, adding analog inputs to the Pi that does not have an ADC.