Artrage has become my prefered tool to do some quick roughs for layout and storyboarding. But it would be even better if it could provide:

Interactive perspective grid (as layer) - adjustable for every perspective you can think of (....or didn't think of before you used it!)

Interactive basic human proportion model (as layer) - and hey, we are talking about bits and bytes here, so why not make it a free rotatable and scaleable puppet!?

Those (in fact very traditional) tools would not only be great for quick roughing out some complex scenes but also they could give a strong basis to fine artwork.