A light version of Spine for the iPad would really be great! Bones, meshes, vertex weights, and a timeline on the go would be a nice addition. I work at my desk all day and it would be nice to set up a character rig outside on an iPad, then toss it back to the desktop for heavy lifting.
ToonSquid on iPad is trying to do this in their last update but it's not as streamlined as Spine's in my opinion. You can make png's into meshes, set bones and even do simple IK. But there's no way go in and alter the weight on vertices individually, which makes it difficult to use.
I wonder if instead of "Spine", you could market a much smaller version called "Vertebra" . In the way Adobe has junior versions of their apps on iOS?