  The various plasma models - incompressible magnetohydrodynamic (MHD) model,
compressible MHD model, incompressible Hall MHD model, compressible Hall MHD
model, electron MHD model, compressible Hall MHD with electron inertia model -
notwithstanding the diversity of the underlying physics, are shown to exhibit
some common features in the Beltrami states like certain robustness with
respect to the plasma compressibility effects (albeit in the barotropy
assumption) and the {\it Bernoulli} condition. The Beltrami states for these
models are deduced by minimizing the appropriate total energy while keeping the
appropriate total helicity constant. A Hamiltonian formulation framework is
used to carry out these variational problems.
