Over the weekend I bought a copy of Wordify from the Mac App Store. Wordify takes an existing picture and a stack of words about that picture and then outputs a PDF that recreates the picture with your words. I made one of my daughter and her cousin and I thought it came out great.
The New York Times was doing something similar to this at Macworld/iWorld and people were lined up around the booth. My wife and kids are really into this.