Under the radar, Steam has kicked off a new service called Steam Broadcasting, which will allow you to peek in on your friends as they play. The service is currently in beta, so you and your friends list pals will need to opt into the Steam Client Beta by going to the Account menu in Settings and changing your Beta Participation status.
You don't even have to do anything to start a stream — once someone chooses to watch your game, a video feed will automatically be sent out! These could be private or public, but sadly, you won't be able to save any of your broadcasts. In order to make use of the service, you'll need to be using either the Steam Client, Google Chrome, or Apple Safari.
Give Steam Broadcasting a shot and see how it suits you!