Valve are introducing a new Steam feature that lets you manage your library and trigger remote downloads from anywhere in the world! Anywhere with an internet connection and browser that is. The feature is currently available via the new Beta client. To get involved, just click File/Settings from within Steam and get downloading. Expect the feature to hit the main Steam client soon.
This means you could feasibly spot a bargain while browsing PCGamer.com in work and start it downloading on your home machine within seconds. You can even check the status of your downloads throughout the afternoon, making it a lot easier to accurately plan your evening's entertainment and maximise your fun-time.