Forget Onlive.. for now.. Gaikai enables you to play Next Gen console games LIVE in your browser, and its started already, theres demos of Mass Effect 2 and Dead Space 2 ready to play on their site and others too. No downloading of any kind. No gaming hardware needed, such as a 3d graphics card, just a pretty fast internet connection required.
Note - 5Mb minimal recommended.
This is only a demonstration of Cloud Gaming so you can grasp the future of where gaming is headed.. Vote only on originality, not on the demos available. :)