  We investigate the pairing and crystalline instabilities of bosonic and
fermionic polar molecules confined to a ladder geometry. By means of analytical
and quasi-exact numerical techniques, we show that gases of composite molecular
dimers as well as trimers can be stabilized as a function of the density
difference between the wires. A shallow optical lattice can pin both liquids,
realizing crystals of composite bosons or fermions. We show that these exotic
quantum phases should be realizable under current experimental conditions in
finite-size confining potentials.
