Here are some good ones:
How To Geek
Windows key – brings up the Metro start screen. You can start typing to search for an app, just like the Win7 start menu.
Win + D – brings up the old Windows desktop.
Win + C – brings up the Charms menu, where you can search, share, and change settings.
Win + I – opens the Settings panel, where you can change settings for the current app, change volume, wireless networks, shut down, or adjust the brightness.
Win + Z – opens the App Bar for the current Metro application.
Win + H – opens the Metro Share panel.
Win + Q – brings up the Metro App Search screen.
Win + W – brings up the Metro Settings search screen.
Win + F – brings up the Metro File search screen.
Win + K – opens the Devices panel (for connecting to a projector or some other device)
Win + , (comma) – Aero Peek at the desktop.
Win + . (period) – Snaps the current Metro application to one side of the screen. (Right side)
Win + Shift + . (period) – Snaps the current Metro application to the other side of the screen. (Left side)
Win + J – switches focus between snapped Metro applications.
Win + Page Up / Down – moves the current app to the other monitor.
Win + Tab – opens the Metro application switcher menu, switches between applications.
Here is a more exhaustive list (but I am not sure all carried from the Consumer Preview).