If you work from home (or in a particularly unfriendly office), Coffitivity masterfully re-creates the sensation of being in a cheery coffee shop. The concept is simple: this site endlessly loops the white noise of people indiscernibly chatting and cups clanking at 40% volume, while you set your own background music at 60% volume. The result is a perfect mix of environmental stimuli that keeps you focused and productive.
Link: Coffitivity