Release status: working
A microSD card reader for the Sanguinololu RepRap electronics.
Where to get it?
It is currently sold already assembled - just plug it into your Sanguinololu.
Printrbot.com: eMAKERshop: 
Our design has fewer parts than others out there, can handle up to 100MHz clock rate should the need arise, and has built-in ESD protection as well. Here's the datasheet http://www.ti.com/lit/ds/symlink/txb0104.pdf. There's a LDO linear regulator on the board for the 3.3V SD supply. SD cards typically use about 80mA so we went with a smaller regulator than Kliment ( SDSL) used.
1. Chip select
This is also confirmed to work great on the Teensylu (by Steph the designer).
Our board isn't directly connectible to the RAMPS/Arduino Mega. You'd need an adapter board/cable of some sort. Theoretically, it should work with RAMPS, but the pins won't be plug and play like the other two mentioned above.
Geek note: Gcodes that relate to the SD card here: 
This design is licensed under CC BY-NC-SA