Over the past decade, new simulation methodologies, such as the Car-Parrinello nb initio molecular dynamics technique, have become increasingly important as tools to study and characterize condensed phase molecular systems. We emphasize the versatility of these new approaches to simulation by reviewing selected applications to molecular crystals, liquids, and clusters, which highlight a range of interesting phenomena. The molecular crystals white phosphorus, nitromethane, and hydrogen chloride dihydrate exhibit molecular reorientation phenomena, methyl torsional motion, and proton-hopping events, respectively. We indicate how, in the latter examples, it is now possible to include quantum effects in the simulation of the proton motion. Ionic solvation and proton transport in water are used to illustrate the current status of simulations of liquid systems. The final topic in our survey deals with the possibility of including the quantum nature of nuclear motions into the simulation methodology of clusters.