In this review we discuss how theoretical momentum-resolved many-body spectral functions can help understanding the physics underlying angular resolved photoemission spectra (ARPES). Special focus is set on phenomena induced by electronic Coulomb correlations. Among these effects are transfers of spectral weight, the loss of quasi-particle coherence, and the sensitivity of these phenomena on external parameters, such as temperature or pressure. For the examples of the metallic phases of VO2 and V2O3 we review results obtained within dynamical mean-field theory, and assess the limits of band-structure approaches. Our discussion emphasizes the need for true many-body techniques even for certain metallic materials. To cite this article: J.M. Tomczak et al., C. R. Physique 10 (2009).