You know when you watch the news and they use those green screens to put the weather behind the newscaster? Want to do it on your phone? Green Screen lets you take a photo and green screen it. You can cut the foreground picture and put it on top of a new background photo to make a new image. This free app automatically creates the green screen effect, can scale, rotate and move images to match the background, rotate portrait/landscape and save photos locally. It also claims that when WP7 permits camera access it will work for live video input. Pretty cool.
You can slight lysee the outline of the foreground image in the sample but it’s a phone…I think the effect still works. I just hit the download button so I haven’t tried it yet, but as a freebie it’s definitely worth checking out.