The Josephson plasma mode has been observed directly in Bi2Sr2CaCuzOa using microwave radiation in the 30 to 90 GHz range. Measurements in an oblique field provide rather conclusive evidence for the plasma oscillations, as well as a determination of the anisotropy parameter 7. In a second experiment, we discuss how the mean free path l0 of quasi-particles may be measured using asymmetric scattering off pinned vortices. In 90-K YBa2Cu3O7, we find that l0 increases rapidly from 90 A at 100 K to 2500 A at 15 K.