Shrink your Gmail layout with Gmail Compactor
The icons aren't the only space-saving feature of Gmail compactor, though. It alos shrinks Gmail's built-in search bar down into the sidebar, and eliminates the Gmail logo. It's up to you whether you think this look feels less cluttered. It does offer the same functions in a smaller space, but the icons also feel a bit a crowded to me compared to the text links, and they take some getting used to.