DxWnd
sourceforge.net
Download DxWnd for free. Window hooker to run fullscreen programs in window and much more... Windows hooker - intercepts system calls to make Win32 programs run in a window, to enhance application compatibility, to enhance video modes, to stretch timing and emulate CD disk data and audio tracks. It is typically very useful to run old Windows games.

Extremely useful for games that only run in full screen. There are many tweaks you can apply to them, such as hooking XInput or mapping a X360 controller to specific keys, force screen size and several other things