[en] Merging neutron stars and neutron stark-black holes binaries are powerful sources of gravitational waves. They have also been suggested as possible sources of cosmic gamma-ray bursts and are discussed as sites for the formation of r-process elements. Whereas the first aspect is undoubtable, the latter two are very uncertain. The current status of our knowledge and of the numerical modeling is briefly reviewed and the results of simulations are critically discussed concerning their significance and implications for potentially observable signals. (orig.)