The Red Ferret Journal points out a slick Japanese language upload-and-convert tool for giving photos that browned-out, decades-old look. Select a photo or paste in a URL (both words are written in English, as luck would have it), and hit the bottom blue button. The photo results aren't returned at full resolution, but, depending on lighting, quality, and, of course, modernity of subject, you can get pretty authentic-looking results without any image editor filters or plug-ins. The site is free to use, and (it appears) doesn't restrict upload file sizes.
Wanokoto [via Red Ferret Journal]