Level-shifted uSD adapter that works with other SPI devices
The Pololu uSD breakout has an onboard 3v3 regulator and level shifters. The DO/MISO signal is tri-state controlled by the CS signal, so this breakout does not interfere with other SPI devices. (Most other breakouts don't do this.) Like Pololu's other modules, this is well-made and well-documented. RobotShop carries many of Pololu's modules and their prices are great.