Stick figures are beyond me. I can manage squiggles and that's about it.
So how do you go about storyboarding something when you seriously suck at art? I wouldn't even know where to start or how.
Another tool which I recently have started playing with is Google's Sketchup. It's free and has a HUGE warehouse of 3D figures, locations, and objects. Very easy to use.
You can import castles, houses, even walk the streets of major cities. Populate it. Take shots and even create animated walkthroughs or check camera angles.
It is easy to use and has several training videos on YouTube.
http://sketchup.google.com/ -- Site that has the FREE download and link to other resources
http://sketchup.google.com/3dwarehouse -- Site for all the 3D objects to create your scene
Because Google links it into its GoogleEarth, large cities worldwide have had massive 3D models created that allow you to actually be on the streets with photorealistic texturing. If you have other tools, you can actually greenscreen characters into the 3D worlds. So if you can't afford a castle backdrop, you can layout your props in a green room and then insert your scene into a generated castle.
But for a simple storyboard, it is a really nifty tool. While it has been used for movie and animation mock-ups professionally, I think it's strength is as a visualization tool. There are more sophisticated tools out there for realistic 3D modelling.
It can import/export Collada (.dae) files. So if you have other 3D software (3D Studio, Blender, Maya, etc.), save to DAE. The nice thing is that you can create new objects and places quickly, even fantasy worlds. If you have DAZ Studio, Bryce, etc., you can easily work between them. And combining it with other tools (AfterEffects, Wax2.0, Voodoo, etc.), you can create some sophisticated looking footage. Both for storyboards and actual filming.
But for a quick storyboard mock-up, check out Sketch-up from Google. It's free, easy to learn and use. It has a large support set of scenes, actors, and objects to choose from--modern, ancient, and fantasy.