The Origami Club web site has some great instructions (and videos) on so many different types of origama from easy to complex, anime style to traditional.
I was looking for something easy to start with for the kids, and this frog "jumped" out at me. (Hah ha)
With the release of Disney's "The Princess and the Frog" on DVD this week, a frog craft could be right on the money.
I wonder if there is a way someone could make pre-printed paper with where to make the folds for easy origami. That would be an interesting kids craft project. Use some scanning software and make origami by the numbers.