TingedAce released a new version of Xnand Healer GUI:

A complete GUI to help you uncripple your Xbox 360. Now updated to check and fix NAND dumps!!!
Requires Nandpro 2.0d or 2.0e and FindSecData 0.62.

I've updated XNandHealer with a couple of useful new features. The main thing about this release is that you will no longer need to (although you may still want to) dump a NAND in full several times in order to get a match. Now you need only dump once and patch it if it contains any errors. This should save hours of time at the dumping stage, especially if you're using LPT. Right now it only supports small block 16MB NANDs, but I should be able to add Big Block NANDs in a future update.

All features have been pretty well tested with 16MB NANDs, however as with the last version I was only able to check the uncrippling feature with 16MB (Pre-Jasper) and 256MB (Jasper) images.

New in v 0.3
* Added new capability to analyze and report the integrity of each NAND dump - it reports bad blocks and ECC error blocks (BB NANDs not yet supported)
* Added "Fix NAND" feature to automatically re-dump any offending blocks and patch them into the original dump (BB NANDs not yet supported)
* There is also the option to re-dump the bad blocks, although they shouldn't matter (since they've been remapped) you may occasionally need to re-dump the bad block just to get an overall matching dump and increase confidence.
* Added "NAND Info" tab, which displays any remapped blocks and ECC error blocks and some basic info about the file (BB NANDs not yet supported)
* Added very basic Hex Viewer, more of a debug feature but allows you to view dump by block/page.
Official Site/Download: http://www.rigid360.co.uk/Downloads.php