Carbon nanotubes, buckyballs (C₆₀) and materials with nanoporosity represent novel substrates for gas adsorption. This situation has attracted significant experimental and theoretical attention due to many possible practical applications as for example gas storage, gas separation and gas sensors. These studies resulted in a wide variety of interesting behaviors. In this talk I will review some of the properties of gases in these nanostructures that are results of computer simulations and model calculations. For example, Xenon adsorbed in an array of buckyballs form a honeycomb lattice gas with a lattice constant significantly larger than in most traditional surfaces. Gases adsorbed in carbon nanotubes form commensurate lattices or quasi-one dimensional striped phases.  The effective dimensionality of these adsorbates can be higher than 4.