Low-energy, near-horizon scaling limits of black holes which lead to string
theory on AdS(2) x S-2 are described. Unlike the higher-dimensional cases,
in the simplest approach all finite-energy excitations of AdS(2) x S-2 are
suppressed. Surviving zero-energy configurations are described. These can
include tree-like structures in which the AdS(2) x S-2 throat branches as t
he horizon is approached, as well as disconnected AdS(2) x S-2 universes. I
n principle, the black hole entropy counts the quantum ground states on the
moduli space of such configurations. In a nonsupersymmetric context AdS(D)
for general D can be unstable against instanton-mediated fragmentation int
o disconnected universes. Several examples are given.