  We briefly review three aspects of string cosmology: (1) the ``stochastic''
approach to the pre-big bang scenario, (2) the presence of chaos in the generic
cosmological solutions of the tree-level low-energy effective actions coming
out of string theory, and (3) the remarkable link between the latter chaos and
the Weyl groups of some hyperbolic Kac-Moody algebras. Talk given at the
Francqui Colloquium ``Strings and Gravity: Tying the Forces Together''
(Brussels, October 2001).
