  Voids are dominant features of the cosmic web. We revisit the cosmological
information content of voids and connect void properties with the parameters of
the background universe. We combine analytical results with a suite of large
n-body realizations of large-scale structure in the quasilinear regime to
measure the central density and radial outflow of voids. These properties,
estimated from multiple voids that span a range of redshifts, provide estimates
of the Hubble parameter, $\Omega_m$ and $\Omega_\Lambda$. The analysis assumes
access to the full phase-space distribution of mass within voids, a dataset
that is not currently observable. The observable properties of the largest void
in the universe may also test models. The suite of large n-body realizations
enables construction of lightcones reaching $\sim$3,000 $h^{-1}$Mpc. Based on
these lightcones, we show that large voids similar to those observed are
expected in the standard $\Lambda$CDM model
