I've used SyncBackSE from 2brightsparks.com to sync my home and work desktops via USB key daily and my entire data partition via external USB drive (bi-weekly or so) for almost four years now. For my purposes it works great, serving as both sync and backup, maintaining all of my data on three drives. It performs well and has more settings than you can imagine! What's more, many of them are actually useful! There are now three versions, free and two paid tiers. Definitely worth downloading the free version to gauge whether the performance will meet your needs...

Congrats all, this has to be one of the longest threads of this nature! It reflects my belief that, at least while you're sitting at it, as your primary channel of information, the monitor is more important than the machine. I'm a monogamous resolution junkie fortunate enough to be running 2560x1600 where looking at a page of code in portrait mode is so incredible and feels so weird that once was enough. I normally just run putty and firefox side-by-side with thunderbird an alt-tab away. I've never tried multiple monitors but it sounds like it serves a lot of folks well. I've just imagined moving the pointer across the no-mans-land that lay between would be annoying. One thing not discussed is monitor height. Before getting the 30"-er and a real mounting arm for it, I'd always placed monitor low (especially as that's where CRTs tended to end up). With the (so wonderfully sprung it feels counter-balanced) mounting arm, I find myself nudging the monitor up bit-by-bit and more comfortably able to utilize the entirety. Finally, to those depriving themselves of their dream display, no matter what it may be, it's a tool of your trade and, even if doesn't make you more productive, it's worth it to improve your quality of life and make you a little happier whilst wasting away worshiping the once phosphorus gods...