ADVANCED CHARACTER CONTROLS
Since bones have now evolved into character controls, we need a way to create more clean/intuitive character controls with them. So, the ability to assign vector/raster images to bones and allow the user to grab those instead
of the bones. That way we can create nice control interfaces for the animator.
I imagine you could do this by putting a bone layer into a group with other image/vector layers. Then in the constraints palette, each bone could have a drop down where you select the image you want to attach to the bone. You could then position and scale the image so it lines up with the bone depending on how you want it to move, like an arrow for a dial or a dot centered on the bone origin for a slider button, etc. Then you could hide the bone and the interface would be clean.
Speaking of sliders, I also would want a way to constrain bones to a path. Like follow path, but for bones. That and/or you could also draw walls around your bones so the bone can't move outside a designated region. That way you could make character control sliders where the bone slider buttons (see above) can only move as far as they were designed in any direction. I imagine these paths would also be found on a vector layer in the same group as the bone layer. That way there aren't any hierarchical issues.
Lastly, it would be nice, then, when you're animating, to be able to manipulate certain bones, like character control bones, no matter what layer you have selected. That way you could have multiple characters, and sub bone structures manipulatable without having to select the layers. Maybe a check box that you can check on each bone layer that allows bone manipulation no matter what layer you have selected.
EDIT: Last, make sure non of these bone constraints/abilities are actually isolated to character controls. Because just like everything else, I can already see how bones following paths and hitting walls would be really cool elsewhere.
Sorry for the long post.