Two requests would be a expression to get the current particle count and also a way to destroy all the current particles.
I am thinking more like 'after pressing spacebar destroy all' etc rather than a destroy zone but i don't think setting up a zone allows that. I tried to destroy the object also but that did not work either so something like this would be quite useful.
With the main library you can also use images and SWF but i didn't see any way to do this. If it could use a active, image or external file etc that would be really cool but i am guessing that would be more complex to do in a extension.
After testing this though it's really cool, i have got some great results and also ported some of my original AS3 particle setups i made. Thanks for all your great extensions.