I thought having a forum thread with windows tips and tricks would be fun. This can be anything from simple keyboard shortcuts to registry modifications.
Win + Left/Right Arrow - snaps the current window to half screen.
Ctrl + W - Closes the current window
Regedit\HKEY_CURRENT_USER\Control Panel\Mouse (Windows 7) - Change mouse hover time (in ms). I always reduce this from it's default 400ms so that window previews on the taskbar pop up faster. Must log off or restart for changes to apply.