Windows 8's Modern interface is loved by some and hated by others, but if you've got a Modern app, your choices of screen size were limited up until now. Stardock's ModernMix gives you that control.
Windows 8 style apps are designed to run either full screen or snapped to the side within a fixed format, which is acceptable if you're using a touch interface, but could be an issue for a mouse user who wants direct control over the app's window size. Start8's ModernMix offers the ability to run Modern apps in windows with absolute positioning, as well as allowing you to close them with a click. It's still in beta for $US4.99 with a 30 day trial available.