Album Art The Same for Artist

For one particular artist on my iTouch, I have about 90 songs from him. (lol yeah I know.) Some of them have album art but for the vast majority, they have none. But for some reason, all the song that don't have Album Art, appear on my iPod with the same album art as one of the songs from him.

In other words, I have one song with album art, and then the rest of my songs from the same artist that have no album art, all display the same album art as that one song.

Any help?

First thing to try is using the Advanced - Get Album Artwork in iTunes.

For the few that doesn't work on (usually because iTunes doesn't have that album or the music is labeled incorrectly go to Amazon and find the album.
Drag the cover of the album to the desktop.
Open up iTunes and highlight all the songs in that Album.
Right click and select Get Info
Go to the Artwork tab
Either drag and drop the cover into the box or click the Add button.