My wife loves the HP software that came with her tablet, as it allows drag and drop into the play queue.
Its also that type of thing that I think MC can improve on, that being the really tactile based experience.
It's another reason why I think MC's Theater View skinning engine needs to be improved, to allow for people to really customise the application to their desires. The basis is there and works really well with the flicking and menu dragging etc, but the ability to do somethings easily is lacking (as in the drag and drop example).
The Root menu is another area that can be improved for the touch experience. While the current system works well for remotes etc, a system of tiles etc may be a better option for touch use.
Also, - can the windows flicks be disabled just a for a particular application?