What is the NANDFlasher?
THE FIRST PROFESSIONAL TOOL FOR ALL YOUR XBOX 360 HOMEBREW NEEDS !!
The nandflasher is basically a JTag device that lets you read and write to the X360 NAND. This requires an Exploitable console. Hmm, is my console xploitable? Well if you have a dash kernel before 8xxxx and the console was manufactured before Jun 18, 2009, then you most likely can use this device.

The product can be pre-ordered right now from divineo.com and is scheduled to ship on March 26th, 2010. The new "NANDFlasher" by Maximus will retail around $45 USD. There are two different models and both come with a wiring kit.