If you have not had a look at it yet, you could be missing out! The Windows 8 engineering team at Microsoft Corporate Offices has created a blog called the Windows 8 App Developer Blog where you can gain valuable insights on how to create Metro Style applications.
Learn how to create a great tile experience, keep your apps fast and fluid and learn how to ensure your app has the best performance. On the Windows 8 App Developer Blog, you can keep checking back every day or two for new tips and tricks.
Check it out here!