Windows XP, I believe, introduced a very useful context menu option, called, "Open With" when someone clicks on an icon of a certain kind. My question is how to add my own program into that list. (See screenshot attached)
So, just poking around in the registry under HKEY_CURRENT_USER/Software/Microsoft/Windows/CurrentVersion/Explorer/FileExts you'll find a list of extensions. Under some of them you'll find OpenWithList. You could try adding an entry there.