Products of hyperbolic metric spaces
  Let (X_i,d_i), i=1,2, be proper geodesic hyperbolic metric spaces. We give a general construction for a ``hyperbolic product'' X_1{times}_h X_2 which is itself a proper geodesic hyperbolic metric space and examine its boundary at infinity. 
Thomas Foertsch, Viktor Schroeder (University of Zurich)