NUS Downloader, or NUSD, is a PC Utility designed to allow easy access to the resources present on Nintendo’s Update Servers. Using this tool, you can download, pack, and decrypt many system titles into WADs ready to install.

Changes:

Access a local database (database.xml) of title IDs, along with versions/regions/etc.
With database selection, IOS WADs are given Nintendo naming convention (ex: IOS60-64-vXXX.wad)
Mismatches are identified as Safe or BAD.
Command line arguments can be passed to the GUI.
Korean key (kkey.bin) support. Useless as far as I know, nothing on NUS uses the key…
Downloading failures are now described in more detail (401 vs 404, etc.)
Status Box has a clear button; it is auto-cleared when starting a new download.
UserAgent changed (again) to the Wii updating one.
A title’s required IOS is shown in the download log.
Trucha signing titles (Still in Beta/Alpha stages! By default it is disabled, to display the feature, click the progress bar on the main form)
Trucha signing features the following:
TMD editor (Change IOS needed, title version, title ID)
Ticket editor (Change DLC Amount, Common Key needed, Time limit)
Contents editor (Add/Remove Contents, Set shared status, Set boot content, Add trucha bug to content [only decrypted contents have support so far!!])

http://wiibrew.org/wiki/NUS_Downloader