I was watching an episode of Scott Kelby's "The Grid", which featured his oft-used "fake-pano" crop. Specifically, Scott used a 1:2.39 height to width crop ratio. Editing an image yesterday morning, I wanted to give it a panoramic feel. Aperture doesn't have a canned panoramic crop, but it's trivial to make one with a Custom crop.

From the Crop tool, select the "Custom" aspect ratio. Aperture doesn't accept decimal values, so set the width to 239 and the height to 100. Then, crop away!

Maybe the next release of Aperture will allow custom crops to be saved. Until then, you can always create a preset of just the Crop adjustment to save a few keystrokes.