  I present a review on non relativistic effective energy--density functionals
(EDFs). An introductory part is dedicated to traditional phenomenological
functionals employed for mean--field--type applications and to several
extensions and implementations that have been suggested over the years to
generalize such functionals, up to the most recent ideas. The heart of this
review is then focused on density functionals designed for beyond--mean--field
models. Examples of these studies are discussed. Starting from these
investigations, some illustrations of {\it{ab--initio}}--based or
{\it{ab--initio}}--inspired functionals are provided. Constructing functionals
by building bridges with {\it{ab--initio}} models represents an extremely
challenging and timely objective. This will eventually reduce/eliminate the
empirical character of EDFs and link them with the underlying theory of QCD.
Conclusions are presented in the last part of the review.
