Windows: One of the biggest annoyances of the new Windows 8 Start Screen is that it takes you out of whatever you're doing. Start Screen Customizer can help soften the blow.
The app allows you to set a custom transparency level on the Start Screen so it feels a little less like you're switching to a completely different app. Instead, the Start Screen appears as an overlay not unlike the Dashboard on OS X. It's a small change, but it may make the transition less disruptive.