The two screens in the middle are 30" Dell U3011 (2560x1600). They can support multiple connections, which I use to toggle between disparate connected systems. The quad on the left is also split between a couple of other systems. I use Mac OS X, Linux and Windows primarily and in this setup, I can get to those environments all at the same time. I generally run linux and VMs on the side rigs, but they can boot into Wintendo for multiboxing, or monitoring online games while I work.
Oh and I guess it goes without saying that I am a *huge* proponent for using monitor arms to maximize deskspace :).