  Gravitational Wave Astronomy is becoming a reality as Earth-based
interferometric gravitational-wave detectors reach the design sensitivities and
move towards advanced configurations that may lead to gravitational-wave
detections in the immediate future. In this contribution, I briefly summarize
the basic characteristics of this new area, the discovery prospects and the
potential for fundamental physics. Then, I present results of some
investigations of two different sources of gravitational waves that are
potential targets for present and future planned observatories. First, I will
discuss the generation of gravitational radiation by non-linear effects arising
from the coupling between radial and non-radial oscillations of neutron stars,
which may produce distinctive gravitational-wave signatures. The gravitational
radiation emitted by these sources is in the frequency band of Earth-based
detectors. And second, I will discuss the gravitational-wave emission during
the inspiral of extreme-mass-ratio compact binaries. In this case, the
gravitational waves have low frequencies, inside the frequency band of space
observatories like LISA.
