  The potential of the Sunyaev-Zel'dovich (SZ) effect for cluster studies has
long been appreciated, although not yet fully exploited. Recent technological
advances and improvements in observing strategies have changed this, to the
point where it is now possible to speak of this subject at a meeting devoted to
{\em surveys} in Cosmology. We will discuss SZ surveys by distinguishing what
may be called {\em pointed surveys}, dedicated to pre-selected clusters, from
{\em blind surveys}, those searching for clusters in blank fields. Surveys of
the former type already have significant numbers of clusters with very good
signal-to-noise images; surveys of the second type are currently possible, but
as yet not undertaken. The discussion will focus on the kind of science that
can be done in this ``new territory''.
