Once you've moved the window with the arrow keys you can also use the mouse to move the window. The problem with this is that it's _slow_, and it doesn't actually work on some software. Some non-native window frameworks like to disable (or don't implement) all hotkeys by default, including f10, Alt+space and sometimes even the tab key. IMO the only reason for a program to disable the standard windowing mechanics is because it's intended to be used as an overlay (programs like launchy or slickrun).
You wanna freak out anyone under the age of about 45-50, use the [Ctrl]-[Ins] / [Shift]-[Ins] / [Shift]-[Del] shortcuts while they're watching your keyboard. Everyone nowadays only knows those Apple-copied [Ctrl]-[C]/[V]/[X] ones, and thinks they're the God-given Standard.
Works really well when the window's title bar has been moved offscreen for some reason.
IBM's CUA for the win. https://en.wikipedia.org/wiki/IBM_Common_User_Access