2D Flip Book Style Animation Software

Does anyone know of some easy to use 2D Flip Book Style Animation Software.

Currently I was playing with Flip Boom All-Star (from Toon Boom) and it did the basic job well. That was until I found out how unstable it was when I brought in my own images.

Attachment 99725

I may just have to use the animation feature in Photoshop.

Any ideas of other products (besides from the toon boom line) that do animation (I don't really care about character modeling shading).