Google News Archive now lets you visually browse newspapers from several newspapers, including The Montreal Gazette, The Sydney Morning Herald, St. Petersburg Times, and Pittsburgh Post-Gazette.
Being able to scan through the real digital copy of old newspapers is actually kind of fun -- I find myself looking at the ads and classifieds more than the content though -- some of the things you can find are quite amusing.
I still have a problem with the visual navigation though -- is this type of thing actually useful? It's easy to navigate to a specific date range which is nice, but the thumbnails of newspapers is useless. I can think of several pieces of information that means more to me than an image -- like maybe the number of pages, quality (because I've found a few older ones that are basically illegible), or the headlines.