  We discuss the general link between mode-coupling like equations (which serve
as the basis of some recent theories of supercooled liquids) and the dynamical
equations governing mean-field spin-glass models, or the dynamics of a particle
in a random potential. The physical consequences of this interrelation are
underlined. It suggests to extend the mode-coupling approximation to
temperatures well below the freezing temperature, in which aging effects become
important. In this regime we suggest some new experiments in order to test a
non-trivial prediction of the Mode-Coupling picture, which is a generalized
relation between the short ($\beta$) and long ($\alpha$) time regimes.
