Any time you want to spruce up your mind while you are shackled to your computer, try changing the desktop background image to something pleasing to you. It will make a visible difference to your mental setup. It works every time for me. Some of the themes which lifts my mind when it is bogged down with work are nature themes, abstract art and beautiful cute looking wild animals.
A good wallpaper should work in making your computing experience a tad lighter without being a distraction.
Vlad Gerasimov runs his own design company called Vladstudio which specialize in web design and development, database-driven sites, skins, icons, logotypes and collateral graphics. In his spare time, he is in the habit of creating beautiful looking wallpapers which he then makes available to all in different screen sizes to adorn your desktop including for dual monitors.
He is also purported to be a contestant in the Oxygen Wallpaper contest.
Of his diverse set of wallpapers, I do like the ones shown below. They are quite pleasing without being an eyesore.