I saw these images pop up in my FFFFOUND! Rss-feed from time to time and was impressed by them but somehow never bothered to check out who made them. I always was under the impression it was Photoshopped, but apparently it’s double exposures which makes it even better.
See the double exposure gallery here: http://www.flickr.com/photos/danmountford/sets/72157625371295037/
And the rest of Dan’s work here: http://www.flickr.com/photos/danmountford/sets/