When you place an item into a wish list, you will see 5 strawberries next to the item. The number of strawberries indicates your interest level in that item.
It's sort of a "how much do I want it" ranking... I usually give the toys I want really bad a 5 and things I like but am not sure about a 3. Then when you go to your wishlist you can order the items by how much you want them.