Save Album Art as folder.jpg will export the artwork of the selected tracks or tracks in the selected playlist as a JPEG image file named folder.jpg to the folder which contains each selected track's file--presumably the track's Album folder. Many third-party music players and systems (Sonos, for example) may look for a "folder.jpg" here to use as display artwork.
Very similar to the just updated Save Album Art to Album Folder.
This latest version makes some tweaks for Mavericks compatibility.
More info and download here.