I built an Arduino data-logger around our 64Mbit Flash memory (BM003) module yesterday. The BM003 is a carrier board for the Macronix MX25L6445E, an SPI Flash memory IC. Flash memory retains its values for years after power is removed. The module has some signal conditioning circuitry to allow you to use 3.3V or 5V i/o connections, and a linear regulator to provide 3.3V to the IC if that’s not available in your system. The Arduino program accepts serial commands at 9600BPS to erase the EEPROM, take and store 3 analog measurements in memory, or read back all of the data stored.