Another faster way of batch downloading album art is using a new tool called DisCoverArt.
DisCoverArt is a command line tool to download albumart (coverart) for mp3 music files based on artist and title or album.
The target audience are people who have organized their music collection in a single track artist+title way iso based on albums or album directories.
This tool can be used stand-alone, but it was aimed to be used in conjunction with mp3tag.
See this topic: /t/14521/1