In this day of age, it's very practical to have a Windows 7 installation on your USB key, for many netbooks and devices don't come with CD/DVD drives anymore.
Yes you read it right, Heather Dewey-Hagborg makes 3D portraits from the DNA collected from objects like cigarette butts or chewing gums she picks from sidewalks, tossed away by strangers.
Mac OS X Mountain Lion has 43 secret desktop wallpapers hidden in one of its folders. They are all beautiful, high quality and this is how you find them.