MusicZen is a portable tool for moving or copying a set of MP3s, renaming and organising them into folders at the same time.
The program works by reading the tags in your MP3 files. By default these will be organised into folders for each artist, then album, but there are several other options (Artists\Years, Artists\Years\Albums, Artists, Albums, Years\Albums, Years).
Each file will be renamed along the way, which may help if you've no consistent naming structure right now. By default they'll be named using the track number and title, but this changes according to your folder structure. If you're organising files according to their year, for instance, they'll given the album name first, then the track number, and finally the song title.
You're also able to decide whether files will be copied or moved, and MusicZen will handle everything else itself. This includes sorting out duplicates; if a file it's moving already exists, then the original will be left in the source folder. And if some MP3s have no tags then they'll be saved in an "Unknown" folder.
While this sounds like it could be quite complicated, a straightforward app-like interface means it really isn't. At a minimum, all you have to do is specify the source and destination folders, and click "Organize". And even if you click the Preferences tab, everything we've mentioned here can be defined with just three buttons.