In order to study these pattern formation processes, we introduced lattice gas models on deformable surfaces [1] [4], which automatically incorporate the mutual exclusion between the molecules and provide an intuitive understanding of the observed behavior in terms of nucleation and growth processes. The same approach also leads to a concise description for the binding cooperativity of membrane-anchored molecules and to a generalized 'law of mass action' for membrane adhesion [7], with binding constants that are governed by the nanoscale roughness of the membranes [8].