SpriteMods has published their design for a DIY NAND flash reader.
When security-testing the ‘secure’ USB-sticks I got my hands on in the past, I needed a way to directly read the NAND-flash these sticks use to store the data on. For that, I created a quick hack: a NAND-reader consisting of a small PCB the flash had to be soldered on and a parallel port interface. There was no voltage conversion apart from some resistors to limit the current from the 5V parallel port to the 3.3V flash chip and the software was a horrific hack, but the contraption worked: I now had a tool to read out NAND flash, even if it was tied together with the solder and the software equivalent of lots of duckttape.
Their latest design uses USB instead of a parallel port, accomplishing this using a FT2232H module. (This module retails fo around $27 from Digikey.
For the schematic and source code, visit SpriteMods.