I actually found something in Photoshop CS5 that makes me a happy Panda. Non-Destructive Cropping.
Cropping non-destructively After you create a cropping rectangle with the Crop tool, select Hide from the options bar to preserve the cropped area in a layer. Restore the cropped area anytime by choosing Image > Reveal All or by dragging the Crop tool beyond the edge of the image. The Hide option is unavailable for images that contain only a background layer.