One for the US only, unfortunately, but if you've been meaning to give game-streaming service OnLive a try, Deus Ex: Human Revolution could be just the kick-start you need. Buy a copy from a store (not, unfortunately, a digital download version) and you'll get a special code that also unlocks it for streaming over the wires. This means you can play it wherever you go, on any PC, Mac, or even a TV... as long as you have a hefty internet connection to get the bits to you fast enough to play it.
OnLive's general service costs $9.99 a month for unlimited access to games like the original Deus Ex, Borderlands, The Witcher and Just Cause 2, plus special offers on other games. To make sure your connection is up to the challenge of cloud computing your way to gaming bliss, download the system checker first. OnLive is currently scheduled to launch in the UK on September 22nd.
Update: Commenter dancingcrab mentions has been told by OnLive that this offer only works with retail copies purchased from Gamestop.