Manual Edit - Free
SongKong also provides manual editing in both Desktop and Remote modes, and this is fully functional with free Lite license.
This is especially useful in Remote mode because it allows direct editing of music files on devices such as Nas servers without having to copy the files to a desktop computer to be modified by a conventional music tagger and then copied back.
Manual Editing uses a spreadsheet like UI. This gives the quickest way of editing multiple fields and files.
Google Image search
Comes with a handy Google Image search for looking for missing artwork