GIMPShop
Have you ever looked at GIMPshop? It's a flavor, or variety of the GIMP. Someone decided to doctor up the GIMP to make it look and feel more like Photoshop, especially for digital scrapbooking. It's also free, just like the regular GIMP. I haven't looked at it myself but I'm curious to hear more about it, especially from someone who has used the GIMP as well, to hear a comparison.
Here is a link for more info if you are interested: http://www.gimpshop.com/
Happy Scrapping! ~Jen