NANDCompare v1.2 has been released by Rab. NANDCompare is a tool which will verify Xbox 360 NAND dumps.

The tool has two functions:

Compare 2 nand images
Better than simply using md5 as it tells you which blocks are mismatched, which allows you to reread only those that are in error rather than the entire chip (speeding up the process)
one use of this is when verifying a write by reading back the nand and comparing it against the original you wrote, if you get a bad block just reread that individual block, patch it into the full read and compare again (files are reread each time you click compare, no need to reselect the same files in the gui)

Reconstruct image from 3 bad reads
assumes that read errors don't occur in same place each time, which is true for some read errors (e.g. lpt timing problems), if there is a good reason why you can't read something then this may not be true
this tool cannot recreate a nand out of nothing, if you give it 3 files full of zeros you'll get a recreated nand full of zeros, always look at a dump to make sure it looks correct (e.g. has a microsoft copyright at the top, once you've reconstructed a nand open it in 360 flash tool and make sure it reads ok there)
the tool works by comparing blocks between the 3 files, any block found matching in 2 (or 3) of the files will be considered good, you will be warned if not all blocks can be recovered, in which case you'll need to get more reads or look for a good reason why your reads are so bad

More detailed information including whats new and fixed is available in our Xbox 360 Homebrew Database.

360-Hq Homebrew Database: NandCompare v1.2
Download: here--"