An Android app called RemoteDroid allows Android smartphones to become wireless computer touch pads and keyboards. It's a great solution for people using computers as their entertainment hub. Here's how get it up and running:
RemoteDroid requires a client application to be installed on your Android phone and the server to be application installed on your computer. In order to use RemoteDroid, you'll need to make sure Java is installed on your computer. You'll also need a Wi-Fi network. Once these two requirements have been met, you're ready to install RemoteDroid.
Download the server application from http://www.remotedroid.net/RemoteDroidServer_v1.5.zip.
Extract the files from RemoteDroidServer_v1.5.zip to a folder and double-click on the file, RemoteDroidServer.jar. This will launch the server software. Since it's a Java app, it will run on Windows, OS X, and Linux. Make a note of the IP address that the app lists.
Install RemoteDroid from the Android Market and launch the app. In the box, type in the IP address that the server software listed and tap the Connect button.
Once the client app on your Android device connects to the server app on your computer, the screen on your Android device will change to a touch-pad layout. The large rectangle at the top is the mousing surface and the two smaller rectangles at the bottom are the left and right mouse buttons. The green keyboard icon activates the keyboard.
You can access mouse sensitivity and other preferences by pressing the Menu Key at the RemoteDroid screen before connecting. The trackball preference only applies if you happen to have a device with a trackball. Also, in case you're wondering, multitouch scrolling is supported. Drag two fingers on the mousing surface to scroll.
That's it. Now you've got a remote control for your computer--perfect for controlling a media center PC!