I added a new action into construct's sprite object which allows you to set a distortion point by a layout co-ordinate. This allows you to easy make say 10x10 'point' objects, and loop through them setting the displacement points on a sprite to those points.
Now, for skinning, you basically need to write code that 'sticks' an object onto another object such that if the other object rotates, moves, or resizes, the object that is 'stuck' will reposition accordingly. Skinning then works by 'weighting' these values. So you calculate the position for the object if it was stuck to the arm (for example), and the position of the object if it was stuck to the torso, and then calculate in with weights. eg: position = 0.6 * arm_position + 0.4 * torso_position.
The maths is pretty simple, but making the skin look realistic is an art. In the 3d program 'maya' it allowed you to 'paint' the weight values, so you would select the arm bones, and then the vertices on the 3d model would all become shades of grey determined by their 'weight' value.
Anyway, this is a really advanced stuff! I mean Aquaria won indie game of the year for 2007, and the main character was animated with the same method as my bone movement (as I have illustrated in another thread). I guess we are in 2009 so technology has changed.
What I've been thinking about doing is creating an 'advanced stuff' object, which would embody lots of complicated functions and stuff, such as calculating angles for IK, finding the other side of a triangle, and basically just various calculations that are rather lengthy to write as an expression, but can give your games that 'edge' over other games. Plus machine code is faster at evaluating equations, so it would be faster and easier to use.