Combinations of suitably chosen metal ions and dendritic ligands may lead to giant metal complexes that display interesting spectroscopic properties, particularly as far as luminescence is concerned. This paper reviews some recent results obtained with metal complexes of dendrimers capable of exhibiting: (i) metal-centered, (ii) metal-to-ligand charge-transfer, or (iii) ligand-centered luminescence. The study of the luminescent properties reveals that these compounds can be useful for several purposes, including light harvesting, sensing with signal amplification, and conversion of the absorbed light into emitted light of quite different wavelength (e.g., UV light into IR light).