I just came across this offer on the Microsoft Xbox hardware website and I had not heard about it before so wanted to get the word out:

Pre-order Kinect or the Xbox 360 4GB Console with Kinect today, and at launch receive a token to download three exclusive game levels for Kinect Adventures, the game included with Kinect.‡ In Kinect Adventures, you and your friends will explore the world—and beyond—through 20 active adventures to achieve the ultimate status: Expert Adventurer!

What’s included:
  • Two exclusive levels of Rallyball—"Chomper" and "Twisters"—where you challenge multiple waves of spinning and chomping Rallyball patterns!
  • One exclusive level of Reflex Ridge, "Champion," where you dodge obstacles, collect pins and race against time.
  • An exclusive Kinect Adventures Helicopter prop for your avatar.

You can visit this page to see all the retailers carrying the Kinect for Xbox 360 and Xbox 360 4GB model that this pre-order deal covers.

This is great as anything you get above and beyond the product your ordering is a bonus and I always shop for the best deal!