I don't know about you but my iTunes source list gets crowded. Sometimes I just need a little more space for my list. Command-G gives me that space.
Its menu equivalents (View -> Show Artwork and View -> Hide Artwork) aren't exactly hidden features menu-wise but this option isn't as widely known or as widely used as it could be. It's a simple but convenient arrow to add to your arsenal. And, speaking of arrows, did you know that you could click the top bar in the Artwork display to toggle between displaying the Album art for your currently-playing item and your currently-selected item?