This website www.MusicBrainz.org has a great piece of software called “Tagger” and a not so great, but supposedly getting great program called “Picard.”
I am still trying to figure out Picard, to see if it can download album covers for me, but I am not having much luck as of yet.
But Tagger is awesome. You basically point it to your MP3 collection, and it will attempt to match up your MP3s with their database based on a “music fingerprint” and then it will automatically set all the tag info as well as rename the file.
So this means if you have an MP3 of Pink Floyd’s Breath from Dark Side of the Moon but the MP3 has no ID3 info and is named PinkF.-Breath.mp3, it will most likely look at the audio and match up the mp3 with their database and put it into Pink FloydDark Side Of The Moon1 – Breath.mp3 or however you tell it to rename files.
I just need to find a similar program to get album covers too.