This is a suggestion for the official powdertoy, I don't want to make my own version
I think the special section should have a few tools rearranged, mostly Vac and Air should be together in the lineup and Cool and Heat should be together as well
as for my suggestions: between Vac and Air should be ANOR (or something) which is a normalizer for air pressure (it brings the pressure in the affected area to the default) similarly, there should be a HNOR (i dunno..) between Cool and Heat to normalize temperature for affected particles.
I think these changes would be useful because it gives a bit more structure to the special category and also sometimes I want to reset temperature or pressure in a simulation without pressing the "new sim" button, and it's hard to do that with the current tools.
oh and as a side note (I know it has been suggested before, but it's a very good suggestion) I think there should be an "are you sure" dialogue that pops up when you click the new simulation button, as I've often accidentally deleted my work from a slip of the mouse when I didn't mean to click the new sim button.
As another side note, I think we're going to need more space in the special section :V