We present the discovery of three new quasars at z>6 in ~ 1300 deg2 of Sloan Digital Sky Survey imaging data, J114816.64+525150.3 (z=6.43), J104845.05+463718.3 (z=6.23), and J163033.90+401209.6 (z=6.05). The first two objects have weak Lyα emission lines; their redshifts are determined from the positions of the Lyman break. They are only accurate to ~0.05 and could be affected by the presence of broad absorption line systems. The last object has a Lyα strength more typical of lower redshift quasars. Based on a sample of six quasars at z>5.7 that cover 2870 deg2 presented in this paper and in Paper I, we estimate the comoving density of luminous quasars at z~6 and M1450<-26.8 to be (8+/-3)×10-10 Mpc-3 (for H0=50 km s-1 Mpc-1, Ω=1). Hubble Space Telescope imaging of two z>5.7 quasars and high-resolution, ground-based images (seeing ~0.4") of three additional z>5.7 quasars show that none of them is gravitationally lensed. The luminosity distribution of the high-redshift quasar sample suggests the bright-end slope of the quasar luminosity function at z~6 is shallower than Ψ~L-3.5 (2 σ), consistent with the absence of strongly lensed objects. Based on observations obtained with the Sloan Digital Sky Survey, and with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium; on observations obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, made possible by the generous financial support of the W. M. Keck Foundation; on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximillians-Universität München, and Georg-August-Universität Göttingen and based on observations in the framework of the ``Calar Alto Key Project for SDSS Follow-up Observations'' (Grebel 2001), obtained at the German-Spanish Astronomical Centre, Calar Alto Observatory, operated by the Max-Planck-Institute für Astronomie, Heidelberg, jointly with the Spanish National Commission for Astronomy.