It's an incredible oversight by Apple that iTunes does not import album covers. iTunes Art Importer comes to the rescue however by allowing you to have all your favourite album covers alongside your favourite tunes - and it looks great.
The program is connected to the Amazon database and adds the album cover of the song that is playing at any one time. It doesn't always offer you the right album unfortunately although it prompts you to select one from a list of probable candidates. You can configure the program to automatically choose the one that it thinks is correct although you may end up with Billy Joel instead of Billy Ocean.
When you start up the Importer, iTunes will also start up if it's not already running. The best way to use the Importer is to select all the tracks for a single album in iTunes and click the search button in the Importer (denoted by the magnifying glass). It will then query Amazon.com for albums that match. If multiple albums are found, the best match will be automatically selected. When the correct album is selected and the album art is displayed on the left, simply click the Import button and you're done.
This is not an essential program for music lovers but it can deepen your appreciation of your collection by learning about the album cover info.