  This paper reviews some recent progress on QCD functional integrals at
nonzero chemical potentials. One issue discussed is the use of QCD inequalities
for this regime. In particular, the positivity of the integrand of particular
Euclidean space functional integrals for two-flavor QCD with degenerate quark
masses is used to demonstrate that the free energy per unit volume for QCD with
a baryon chemical potential $\mu_B$ (and zero isospin chemical potential) is
necessarily greater than the free energy with isospin chemical potential $\mu_I
= \frac{2 \mu_B}{N_c} $ (and zero baryon chemical potential). This result may
be of use in model finite density systems. A corollary to this result is a
rigorous {\it ab initio} bound on the nucleon mass. The second major issue
addressed is the so-called ``Silver Blaze'' problem: the fact that at zero
temperature and chemical potentials less than some critical value the free
energy remains as that of the vacuum. This is puzzling in the context of a
functional integral since a chemical potential affects the functional
determinant of the Dirac operator and any nonzero $\mu$ changes every
eigenvalue of the Dirac operator compared to the $\mu=0$ value. The isospin
Silver Blaze problem is solved through the study of the spectrum of the
operator $\gamma_0 (\dslash + m)$. The status of the baryon Silver Blaze
problem is briefly discussed.
