Today sees the launch of Nvidia's "GeForce Now" service (which we used to know as Nvidia GRID Beta). It's a game streaming service for owners of Nvidia Shield products, including the original Shield, the Shield Tablet and the Shield TV.
The idea behind a game streaming service is that the game runs in a data center somewhere. The graphics and sound are streamed down to a thin client (in this case, your Shield device) and your inputs are sent back to the datacenter. The benefit is that you can play high-end games on low cost hardware (and avoid spending time installing or patching games). The drawback (or one of the drawbacks anyway) is that there is always going to be some amount of lag.
It's not a new concept. OnLive tried to offer a similar service and ultimately failed, and Sony has a service called Playstation Now that streams PS3 games to select Sony hardware.
Nvidia says that it can offer 1080P, 60 FPS gameplay via streaming, provided the end user has a sufficiently fast Internet connection (50 Mbps). If you have a slower connection the experience will downgrade to 720P ( 20 Mbps) or even lower, with a minimum requirement of a 10 Mbps connection. You'll also need a Shield controller, of course.
GeForce Now costs $7.99/month and currently includes 50 games. The good news is that you get 3 free months to decide if the service is for you. With a game streaming service like GeForce Now a generous trial is essential because there are so many factors that can impact how good your experience will be (everything from your distance to the datacenter to the infrastructure of your home network and even your tolerance for lag). You can learn more about GeForce Now on the Nvidia blog.