nevermind i found it and its windows only i didnt know if they had one for mac or not. but what i do if itunes cant find the artwork i go
http://albumart.org/ and type the band name or album name in and it finds the cover/artwork and i save the image to my mac, then i select the album and right click on all of the songs that are selected and add that artwork for that album and it works perfect for me i dont mind spending time doing it... but i hope this helps.