Android, iPhone and Windows Phone 7: PC Monitor is a free app for pretty much any mobile device that gives you a ridiculous amount of control over your Windows or Linux computer. All you need to do is install some simple server software and the app on your phone to get up and running in minutes.
This app can monitor and control everything. It looked pretty neat at first glance, but after getting into it and seeing everything it can do it was hard not to be wowed. You can monitor everything from CPU temperature and usage to network status to RAM usage. You can execute commands in the terminal, run Windows Update, restart/shutdown/suspend/hibernate your machine, quit processes, and tons more. This may seem a little nerdy to some, but if you've ever used a VNC app on your touchscreen smartphone you know it's not the easiest way to remotely control your desktop. PC Monitor makes it easier to carry out a lot of regular tasks and see how your computer's doing very easily.
All of this is completely free. It works with Windows and Linux PCs (unfortunately there's no Mac version) and through Android, iOS and Windows Phone 7 mobile devices.
Mobile PC Monitor (Free)