Freaking cool. Didn't know you could do that with the FReepmail system. Do you know if something similar can be used for pinglists? Some time back I make a shell script that would post to a list of people so as to enable some folks to automate pings, but it would be really cool if a carefully constructed URL could do the same thing.
It is cool. I shamelessly copied it from someone else far more talented than I, so I am uncertain how your goal could be accomplished.