Here's my compo entry, started only 2 days ago so there's lots of bugs and wrinkles left in.
All things considered I'm happy with the result, but be gentle...
The clouds are generated by semi-randomly rotating and scaling a single puff of smoke. For the flashes I pick a random puff from a random cloud, make a slightly larger copy of it in the same location, change the color to a nice purple and finally set it's blendmode to addititve. Then it's faded out and removed. The lightning bolts are just a bit of semi-random scribbling.
I had to attach the swf to this post as a download because I haven't got my site passwords around... Which is probably good pratice anyway, but I would've prefered to provide 1-click acces as well for us lazy web surfers.
Ctrl = toggle auto/manual steering (with mouse)
Up/Down arrow = change speed (only on manual steering)
Space = toggle wheather
Enter = Teh Awesome!
[EDIT] I did some tweaking after the comp deadline, see the new version here