GMT's Shannon Powell Hart has a variety of covers that help protect your iPad.
The Survivor cover is made by Griffin and was created to protect your iPad in armored fashion. The cover is touted as a military-duty case with a stand and meets or exceeds military standards. It was tested to endure four different factors: sand/dust, shock/drop, vibration, and wind/rain. The iPad is placed in a case that helps deflect wind-blown rain. That part of the case has also been dropped on a conrete floor from 6 feet. It is able to absorb vibrations and sealed in a thick, rubber case that helps block sand and dust. This cover cost between $79 to $99.
Zagg has a cover that features a keyboard that has bluetooth capabilities. The iPad keyboard is available in a host of colors, leather and polyurethene. The hard shell protects the iPad with a microfiber lining. It features a built in stand and keyboard that only requires you sync it once with your tablet. The removable iPad keyboard allows flexibility and faster typing. I retails for $99.