First I'd like to say that I'm very impressed with the level of talent and artistry in the inkscape community.  Makes a hobbyist like me feel like a definite poser.

The L-System
I really like this feature.  I was just using it to draw the the teeth on a gear.  I don't fully understand how it works though.  Obviously A though F will draw a line forward the specified number of steps.  G though L move the cursor without drawing.  + and - designate a right and left turn respectively and | (i think it's the pipe symbol) is 180 degree turn. 

I am having a hard time with the "[" and "]" that designate remember point on stack and return to point on stack, what's meant by Axiom, and what happens if an X or Y is thrown into the function definition. 

Also, does anyone know a good page/reference for most of the famous fractals? 

Whirl
Whirl also has me a little stumped.  I would think that x,y coordinate specified in the dialog would define the axis of rotation.  I've tried several times to make an object whirl around it's center of mass/symmetry without any luck.  I've use the points designated by the selection dialog which didn't seem to work.  I'm guessing it's one of the corners of the bounding box.  The I tried putting guides through what I thought was the center and using those values.  No luck there either. 

My System
My system seems to get really bogged down when ever I have any significant amount of nodes/objects for inkscape to keep track of.  I'm running Windows XP with a 2.4 GHz Celeron and 640 MB of ram.  I think this is going to become a significant source of headaches for me in the near future.  I want to upgrade.  Thoughts about minimum requirements for working comfortably on a Mac?  I was thinking of trying a Linux system, but decided against it after installing Fedora Core 6 on my PC.  I ran into too many compatibility issues with modems, monitor, printers, and other input devices. But, that's a discussion for another forum. 

Thanks for some great software.  I hope I can contribute in the project in the near future. 

~Aaron