That's pretty interesting. In fact, this and working on the GUI for tiling  have made me think more about on-canvas templates in general. There's  quite a bit of potential for just dropping stuff onto the canvas for  various outcomes (you can turn them on and off). Possibilities include:

1. Clone/iteration templates: the render frame for the tiling tool is kind  of like an on-canvas clone template, right?

The link you provided could be an iteration template. Drop an iteration  area, drop an object inside it, then manipulate the whole to activate  iteration within the area.

2. Kinematic templates: "improves freehand drawing by altering the  cursor's movements."

More info at http://hci.uwaterloo.ca/research/kinematic (really cool  stuff).

3. Deform templates

An idea I've had recently: create a perspective grid (for example, over  the side of a building), and if you grab and hover any object over it  for a few seconds (example: a 2D window design), the object will have an  automatic perspective deform applied to it. Moving the object along the  grid behaves a bit like what happens with the 3D box tool. Also, when you  draw straight lines within the area, they snap to the direction of the  grid's vanishing points.

Another deform template could be a mesh grid that you can edit before  dropping some object onto it (example: a mesh grid to simulate a wavy  flag. You can then drop the 2D design of any country flag onto it)

Although some of it sounds more suited to 3D programs, a user could very  well want to make a wavy flag in Inkscape, or some simple box icons with  decorations on the side for example.

4. Render templates

Basically things you would currently find under extensions -> Render in  Inkscape (L-systems, trees etc.), except once they are on-canvas you can  edit them there.

Of course, although the ideas sound cool, programming would be another  issue. And all that real-time rendering would totally kill a few CPUs.