My investigations of MythTV and Mono has led me to a few interesting things regarding Linux and operating systems. One of the more interesting, although not immediately useful to most people, is ReactOS.
It’s simply an attempt to create an operating system from scratch that is binary compatible with Microsoft Windows. That is it will be able to run Windows binaries (executables and DLLs). It’s far from feature complete but there a few key apps it can run. For a relatively unimportant but visually impressive example, have a look at Unreal Tournament.