The fast expansion of noble gases through pulsed nozzles results in the fast cooling of the gas and the generation of clusters. The interactions of clusters with ultrashort laser pulses characterize the properties of the clusters. On the other hand these phenomena deserve interest even themselves. In case of moderate intensities a cluster is an efficient source of vacuum ultraviolet radiation by generating high harmonics of the laser pulse. Increasing the intensity the clusters will become ionized and a Coulomb explosion occurs. For extreme, relativistic intensities they can be used for electron acceleration, for the generation of ultrashort packages of electrons.  Experimental investigations of these phenomena are planned using UV (KrF) and infrared (Ti:sapphire, OPCPA) lasers.