Finding artwork for your albums requires an account in iTunes but fortunately there are a multitude of programs out there to help plug the gap if you don't want one such as Album Cover Finder.
Album Cover Finder allows you to use the power of Amazon's immense database to assign all your albums with the right cover. Not only this, but it also recalls album reviews, track listings and even concert listings for your favorite artists and albums. You can also choose the size of the artwork that you want to send to iTunes and search by artist, song title or album.
If you find that Album Cover Finder is retrieving results from the wrong country or simply not finding what you want it to, you can make it search according to region (USA, UK, JP, FR, DE and CA). Once you've found it, Album Cover Finder automatically syncs with iTunes to see which albums need covers adding. It's also interesting to read album reviews for your favorite albums although they all seem to be drawn from the same source.
It doesn't always produce the right results but Album Cover Finder uses Amazon's huge database to give you the best chance of finding your album covers.