  We show that the Extended Bargmann and Newton-Hooke algebras in 2+1
dimensions can be obtained as expansions of the Nappi-Witten algebra. The
result can be generalized to obtain two infinite families of non-relativistic
symmetries, which include the Maxwellian Exotic Bargmann symmetry, its
generalized Newton-Hooke counterpart, and its Hietarinta dual. In each case,
the invariant bilinear form on the Nappi-Witten algebra leads to the invariant
tensor on the expanded algebra, allowing one to construct the corresponding
Chern-Simons gravity theory.
