This desktop aims for a large amount of space for work, without the taskbar getting in the way too much.
The wallpaper rotates every 10 minutes between a big selection I've built up. The one in the screenshot comes from here, along with several others in my collection - mostly space/city ones, with a few funny ones for good measure.
I'm using Shine 2.0 as my Windows 7 theme. I've tried several themes, but I just keep coming back to this one.
Also, the cursor theme is Transparency Cursors 2, which has a nice look that matches the Shine theme pretty well.
The taskbar has been tweaked using 7+ Taskbar Tweaker, which, amongst many features, lets you remove the minimum width/height of the taskbar, hide the Start button (you can still click the gap at the top to open it), shrink the Show desktop button, show seconds on the clock (although I've hidden the clock now I've made the taskbar really thin) and so on.
I've also got some other things going on, such as a 4x4 grid of Dexpot virtual desktops, Launchy for starting programs and opening files, and f.lux to dim my screen at night. I'm also using PicPick as a handy screenshot tool, with region selection, rules, whiteboards and a quick editor for blurring/cutting out parts of screenshots.