  This is a personal review of various issues related to massive photometric
and astrometric searches. A complete inventory of variable stars down to almost
any magnitude limit will improve our understanding of the stellar evolution and
the galactic structure. A search for detached eclipsing binaries will improve
the distance scale, the value of the Hubble constant, and the age of the oldest
stars. A search for supernovae will help the determination of cosmological
parameters Omega and Lambda. A search for microlensing events will provide
insight into the stellar mass function, dark matter, and may lead to a
discovery of earth-mass planets.
