Entropic nonextensivity: A possible measure of complexity
  An updated review [1] of nonextensive statistical mechanics and thermodynamics is colloquially presented. Quite naturally the possibility emerges for using the value of q-1 (entropic nonextensivity) as a simple and efficient manner to provide, at least for some classes of systems, some characterization of the degree of what is currently referred to as complexity [2]. A few historical digressions are included as well. 
Constantino Tsallis (Centro Brasileiro de Pesquisas Fisicas, Rio de   Janeiro-Brazil; Santa Fe Institute, New Mexico-USA)