Let (J,g) be a Hermitian structure on a compact nilmanifold M with invariant
complex structure J and compatible metric g, which is not required to be
invariant. We give classifications of 6-dimensional nilmanifolds M admitting
strong K\"ahler with torsion, balanced or locally conformal K\"ahler structures
(J,g).Comment: LaTeX, 24 pages, 1 figur