When you've run out of space on your desk, do what Flickr user sninesix did: make everything float. Rather than leaving the speakers and extra monitor to hog so much desktop real estate, they now hover above and to the sides so there's plenty of room to work.
Although this is a very clever (and attractive) solution, it should be noted that if you're mixing audio you don't want your speakers far above you because they won't be properly aligned. That said, if you're simply listening to music at your desk through great big awesome speakers this downside isn't such a big deal.
For those interested in making their displays hover, sninsix used the Humanscale M8 to get the job done here and highly recommends it.
Humanscale M8 + NEC PA271W [Flickr]