Windows only: Ever realised after you left the house that you forgot to start your BitTorrent client to finish the last of that big download? That wouldn't be a big deal with Application Access Server.
After installing and configuring AAS on your home computer, you'll be able to launch a browser from any computer from which you can start pre-defined apps, kill system tasks, and more. The application isn't the most user-friendly in the world (it's also fairly advanced), so if you're baffled by the app after installation, be sure to take a look at the user's guide (which, admittedly, isn't the most clear, either). The upshot: After launching aas.exe, you'll need to configure your logins and passwords, determine the port that AAS will run from, and configure the applications you want to be able to launch using AAS. (As you can see in the screenshot, I added uTorrent.)
The application even integrates with DynDNS, the service that lets you assign a friendly domain name to your home server, so it's easy to access from anywhere without requiring you to remember your cumbersome IP address. AAS is a free download, Windows only. There are plenty of other solutions for remotely controlling your PC, so if this seems a bit too cumbersome for your tastes, you might want to look elsewhere.