The SparkFun BOB-00544 is a board design with a microSD featuring capabilities.
Breakout board for the microSD socket that is not much bigger than your fingernail. Compatible with the SPI interface found on any SD card, this tiny form factor was created for cell phone storage and is perfect for your next MP3 project! Board comes fully assembled and tested.
The bare socket is available.
Schematic design BOB-00544
Adding SD to a Router - Thanks Jake! Eagle Layout as well!