Personally, I've found one of the more stimulating ways of playing in recent times has been to kind of move outside the free improvised area and work with people who are probably improvisers but they have a particular way of working.
“All of the biggest technological inventions created by man - the airplane, the automobile, the computer - says little about his intelligence, but speaks volumes about his laziness.”
“But now with the living conditions deteriorating, and with the sure knowledge that we are slated for destruction, we have been transformed into an implacable army of liberation.”