I had found a link to some lovely photography of an abandoned Japanese Amusement Park the other day.
I backed up the URL a little bit and found that the amusement parks are just the tip of the iceberg. Start here and keep clicking-- some gorgeous stuff, here is one example:
For more of these, click on the File1, File2, File3 links.
To see some of this in the United States and Europe, check out here, here, here and here. These are by no means the canonical list but they will get you started.
My one regret about moving from the northeast to the northwest is that the buildings here are so new -- there isn't the wonderful architecture and decay so prevalent on the east coast. Spent many a wonderful weekend afternoon in Boston wandering along the waterfront, breaking into the old buildings and exploring, looking at the old machinery left behind.
Its interesting that there are _any_ abandoned _anythings_ in Japan with their population to landmass ratio.