Network congestion games are a simple model for reasoning about routing problems in a network. They are a very popular topic in algorithmic game theory, and a huge amount of results about existence and (in)efficiency of equilibrium strategy profiles in those games have been obtained over the last 20 years. In particular, the price of anarchy has been defined as an important notion for measuring the inefficiency of Nash equilibria. Generic bounds have been obtained for the price of anarchy over various classes of networks, but little attention has been put on the effective computation of this value for a given network. This talk presents recent results on this problem in different settings.