Not just a simple breakout board, this microSD adapter goes the extra mile - designed for ease of use.

• Onboard 5v->3v regulator provides 150mA for power-hungry cards
• 3v level shifting means you can use this with ease on either 3v or 5v systems
• Uses a proper level shifting chip, not resistors: less problems, and faster read/write access
• Use 3 or 4 digital pins to read and write 2Gb+ of storage!
• Activity LED lights up when the SD card is being read or written
• Four #2 mounting holes
• Push-push socket with card slightly over the edge of the PCB so its easy to insert and remove
• Comes with 0.1" header (unattached) so you can get it on a breadboard or use wires - your choice
• Tested and assembled here at the Adafruit factory
• Works great with Arduino, with tons of example code and wiring diagrams

This works with sdfatlib to allow your Arduino or AVR chip to have access to Gigabytes of data!

For schematics, check here.