  There is a resurgence of interest in black holes sparked by the LIGO-VIRGO
detection of stellar black hole mergers and recent astronomical investigations
of jets and accretion disks which probe the spacetime geometry of black holes
with masses ranging from a few times the mass of the sun to tens of billions of
solar masses. Many of these black holes appear to be spinning rapidly. Some new
approaches are described to studying how accreting black holes function as
cosmic machines paying special attention to observations of AGN jets,
especially with VLBI and $\gamma$-ray telescopes. It is assumed that these jets
are powered by the electromagnetic extraction of the spin energy of their
associated black holes, which are described by the Kerr metric, and that they
become simpler and more electromagnetically dominated as the event horizon is
approached. The major uncertainty in these models is in describing acceleration
and transport of relativistic electrons and positrons and simple
phenomenological prescriptions are proposed. The application of these ideas to
M87 and 3C279 is outlined and the prospects for learning more, especially from
the Event Horizon Telescope and the Cerenkov Telescope Array, are discussed.
The main benefit of a better understanding of black hole astrophysics to the
LISA mission should be a firmer understanding of the source demographics.
