The characterization and detection of exoplanet systems
has become one of the most active fields in astronomy. A wide spectrum
of observational tools is used for this, from high-precision
photometry over optical and near-infrared spectra to microlensing
experiments. A powerful, but not very obvious addition to the toolbox
are observations at short wavelengths. I will discuss how X-ray and UV
data can enhance our understanding of exoplanets and their host stars,
and present a variety of related results.