spacedesk is a free program that makes it really easy to use your tablet or smartphone as a second display for your Windows PC. It offers two modes to do this: Extend and Mirror.

Android tablet-side setup Step 1: On your Android tablet, install TeamViewer from the Android Market and launch it. In the first box, enter the ID of the "partner" computer.

First, you need a compatible tablet running Android 3.01 or newer (or a smartphone running Android 2.2 or newer) and Windows XP (32-bit) or Windows 7 (32 or 64-bit).

The iPad is a good bet, of course. For Android tablets, the Google Nexus 10 is a great deal. And the Samsung Galaxy Note 10.1 is also a solid bet, because it also comes with a stylus.

First appearing in Android 3.1, USB Host mode is a neat feature that allows you to plug in USB devices (including game controllers) into your tablet via a USB cable.