A few months ago, Microsoft announced the SmartGlass app for Xbox, a companion application that allows you to navigate and control your console from your phone or, up until recently, 7" tablets. Now, version 1.5 has rolled out that adds support for larger slates. Including 10" devices like the Nexus 10, which is kind of great.
On a larger tablet, the UI actually doesn't look much different from the interface on the TV itself, so it's extremely intuitive. Also, this update brings an always-on state, so your device won't shut off while you're using the companion app. SmartGlass is free on the Play Store and the update is available immediately.