Personally, I never considered album art for my iPod all that important. That has changed now that we have an iPod touch in the family. If I'm missing a lot of album art, the experience of virtually flipping through my music collection, something Apple calls "cover flow," is diminished. iTunes doesn't always offer art for albums I didn't purchase from iTunes. Thankfully, a little GPL-licensed application called Album Cover Art Downloader (ACAD) solved my problem.