I haven’t done any film or television prop work, so I was unaware of them, but the Set Decorators Society of America has quite a handy website. First off, they show off the decor in films which their members have worked on. These are extensive photo-essays showing the sets from these films, often without actors in the way. You can also read interviews with their various members.
Flickr is an incredible source for scans of ephemera from all eras. There is so much to find on there. One of my dreams is to somehow organize and catalog all of this; until then, all I can give you is a somewhat ordered list of things I’ve found. Remember that this only represents a sliver of a portion of what’s available on the internet.