For Cover Art, I start with the Get from Internet like STFeder said. I like 500x500 images so if it doesn't return at least that, I then go to cover sites like:
http://albumart.org/http://www.coverhunt.com/http://www.slothradio.com/covers/Sometimes though I'll just sit at Amazon or Walmart and find them manually. Amazon is nice because sometimes their art isn't good but customers upload better ones. And by all means, when you have a good quality cover art, do a Submit to Internet so it will help the next person.
Again like STFeder, for lyrics, I start with Data Master. After I get what I can from there, I then go to Doof's Lyrics Editor (
http://www.dooftoo.com/lyricseditor.html). I go through every song I have, even if it came from Data Master, just to make sure it's what I want with capitalization and such. I then use his search for any missing ones to hopefully find the lyrics out on a website. You'll find there are some better sites than others. Finally after editing all the lyrics, I upload with Data Master to again help the next person.