The CanonLenses app is a guide to Canon's current lineup of EF and EF-S Mount lenses used by both Canon's digital and film SLR cameras.
You can view all the lenses at once or you can view lenses in a selected category. You have the ability to sort by aperture, minimum focal length and ESP (Estimated Retail Price). You can also search for all or part of lens names.
Each lens has a detail page which provides links to the Canon web page detailing the lens, reviews of the lens from third parties (if available - brand new lenses might not have reviews yet) and information on where to rent the lens in the US (if available).