Mean-field molecular dynamics (MD) techniques are designed to improve phase-space sampling in MD simulations. Reviewed here are theoretical and practical contributions from our group, and the ideas our contributions are based upon, beginning with the original time-dependent Hartree technique, locally enhanced sampling (LES), and a new, purely classical derivation of multiple-copy, mean-field equations of motion. This view is used to provide new insights into approximations inherent in LES, as well as the basis for a recently proposed method, ensembles eXtracted from atomic coordinate transformations (the EXACT approximation).