  Howe's duality is considered from a unifying point of view based on Lie
superalgebras. New examples are offered. In particular, we construct several
simplest spinor-oscillator representations and compute their highest weights
for the 'stringy' Lie superalgebras (i.e., Lie superalgebras of complex vector
fields (or their nontrivial central extensions) on the supercircle $S^{1|n}$
and its two-sheeted cover associated with the M\"obius bundle).
