  We introduce, analyze, and compare two novel methods of Single Photon Cooling
that generically cool and compress molecular gases. The first method compresses
the molecular gas density by three orders of magnitude and increases collision
frequency in trapped samples. The second method compresses the phase space
density of the gas by at least two orders of magnitude. Designed with
combinations of electric and magnetic fields these methods cool the molecules
from ~100mK to 1mK using a single irreversible state change. They can be
regarded as generic cooling schemes applicable to any molecule with a magnetic
and electric dipole moment. The high efficiency calculated, compared to schemes
involving cycling, is a result of cooling the molecules with a single step.
