  We formulate and prove a version of the arithmetic Siegel-Weil formula for
(zero dimensional) Shimura varieties attached to tori, equipped with some
additional data. More precisely, we define a family of ``special" divisors in
terms of Green functions at archimedean and non-archimedean places, and prove
that their degrees coincide with the Fourier coefficients of the central
derivative of an Eisenstein series. The proof relies on the usual Siegel-Weil
formula to provide a direct link between both sides of the identity, and in
some sense, offers a more conceptual point of view on prior results in the
literature.
