Charge transfer in low energy atomic and molecular ion-surface scattering is discussed within a general, time-dependent theoretical formalism, from which the origin of many observed phenomena such as neutralization, population of projectile excited states, alignment and polarization of light emitted by relaxation of such states, and coupling of projectile states to discrete target core states, is evident. Attention is focussed on time-resolved theoretical and experimental studies of the collision complex, designed to obtain a detailed understanding of the interaction. Both emission and adsorption spectroscopies, suitable for such time-dependent studies, are described. Possible trapping of a glancing incidence keV ion beam is reported, suggesting that glancing incidence surface scattering experiments, using both atomic and molecular projectiles, will in future provide important insights into the dynamics of chemical reactions and adsorption phenomena at surfaces. Finally, several of the outstanding theoretical and experimental challenges are reviewed.