The NVIDIA Shield is essentially a game controller with a screen attached so you can take your music, movies and games wherever you go. It lets you stream the PC games you already have over Wi-Fi so you don't have to be in front of the computer to play them.
LinusTechTips was supposed to receive a Shield to test, but it was late getting there, so they decided to make their own using an Android phone and an Xbox 360 controller. They've dubbed the project "Ghetto Shield."
They used an old side panel for the back piece and glued it to the controller's battery pack with epoxy. A piece of Velcro makes it easy to attach or remove the phone.
For streaming, they used a free app called Splashtop, which gives you remote control over your desktop. You'll need to download both the streaming version for your computer and the mobile version for your phone in order for it to work.
It may not look as sexy as the real thing, but if you don't want to pay 300 bucks, it's a pretty good substitute. Check out the video for more details and to see the Ghetto Shield in action.