The Acme Made Infinite Angle case is ultrathin and allows you to prop up your iPad at any angle (at least in landscape mode). It has the auto awake feature built into the case like Apple's Smart Cover. It's really a nice, lightweight case that's also fairly affordable.
Note: This case was originally designed for the iPad 2. Acme Made says it's compatible with the third-generation iPad. However, the company wants you to know that Apple implemented changes to the sleep/wake function requirements in the iPad, "specifically magnet strength and polarity." Since this was not a requirement for the iPad 2, Acme Made says the Infinite Angle's auto-wake feature may not work for some iPad 3 users (the feature worked with my new iPad, but proceed at your own risk).