This is a compositing effect that I created to give the appearance of an old photo. This .blend has a photo that I took, with the effect added to it (this is to demonstrate that it works well on photos too, and not just blender scenes). Be forewarned that it doesn't work so well on some photos (often times they are photos with high levels of contrast that cause problems), as it can 'black out' certain areas. You can also occasionally lose detail; but then again, that happened to a lot of old photos as well ;)
Also keep in mind that the effect may be a little difficult to tweak as the node setup is very large.
Displayed in the screenshot above is a demonstration of the effect; the left half being the affected area, and the right being the original photo.