  We present a catalog of 105 rich and massive ($M>3\times10^{14}M_{\sun}$)
optically-selected clusters of galaxies extracted from 70 square-degrees of
public archival griz imaging from the Blanco 4-m telescope acquired over 45
nights between 2005 and 2007. We use the clusters' optically-derived properties
to estimate photometric redshifts, optical luminosities, richness, and masses.
We complement the optical measurements with archival XMM-Newton and ROSAT X-ray
data which provide additional luminosity and mass constraints on a modest
fraction of the cluster sample. Two of our clusters show clear evidence for
central lensing arcs; one of these has a spectacular large-diameter,
nearly-complete Einstein Ring surrounding the brightest cluster galaxy. A
strong motivation for this study is to identify the massive clusters that are
expected to display prominent signals from the Sunyaev-Zeldovich Effect (SZE)
and therefore be detected in the wide-area mm-band surveys being conducted by
both the Atacama Cosmology Telescope and the South Pole Telescope. The optical
sample presented here will be useful for verifying new SZE cluster candidates
from these surveys, for testing the cluster selection function, and for
stacking analyzes of the SZE data.
