The Canon website in Europe has made the current Lens Work III publication available online as a PDF. This provides details about all the lenses in the Canon catalog, sort of like an expanded sales brochure, but it does contain lots of valuable information about using lenses, optics, and MTF charts, plus there are a lot of great photographs. It's a really excellent resource. Usually published and sold as a book, it is now available as 11 chapters or separate PDFs for free, though at nearly 32 mb altogether, you will need a broadband internet connection to download it.
Click here to download Lens Work III.