  Being dominated by non-thermal (synchrotron and inverse Compton) emission
from a relativistic jet, blazars offer important clues to the structure and
radiative processes in extragalactic jets. Crucial information is provided by
blazars' spectral energy distributions from radio to gamma-rays (GeV and TeV
energies), their trends with bolometric luminosity, and their correlated
variability properties. This review is focussed on recent multiwavelength
monitorings of confirmed and candidate TeV blazars and the constraints they
provide for the radiative properties of the emitting particles. I also present
recent observations of the newly discovered class of ``blue quasars'' and the
implications for current blazars' unification schemes.
