Emily Chang, Gmail engineer has added a new feature in Gmail Labs called “Right-side Labels” to mitigate the problems associated with long lists in both Labels and Chat, where you constantly scroll in order to see Labels. Now, with Right-side Labels enabled, you can see both Labels and Chat buddies at the same time, with one on the left and one on the right. If you’ve a widescreen monitor and lots of emails, this’s pretty handy. You’ve preferreces to move Chat instead of Labels option as well.

Note: these Labs aren't currently compatible with the "Navbar drag and drop" Lab that allows you to drag and rearrange Chat and Labels on the left side.