  I present here a new algorithm to generate families of inhomogeneous massless
scalar field cosmologies. New spacetimes, having a single isometry, are
generated by breaking the homogeneity of massless scalar field $G_2$ models
along one direction. As an illustration of the technique I construct
cosmological models which in their late time limit represent perturbations in
the form of gravitational and scalar waves propagating on a non-static
inhomogeneous background. Several features of the obtained metrics are
discussed, such as their early and late time limits, structure of singularities
and physical interpretation.
