The maximal transmission distance of optical quantum communication is reaching a hard limit imposed by the intrinsic loss of the transmission medium, e.g. optical fibre. A quantum repeater promises to push that limit towards much longer, potentially intercontinental distances. Its implementation relies on the development of efficient and long-lived quantum memories that can store and retrieve the quantum properties of light. Sources of photonic entanglement, tailored for quantum memories, are also necessary and represent a challenging experimental task. I will review the efforts of our group towards the realization of quantum memories based on rare-earth-ion doped crystals (REIC) as well as a matching source of photon pair. This approach has recently allowed us to demonstrate several features that are of great importance for quantum repeaters, and for quantum networks in general. After a brief introduction, I will show how we have successfully entangled two neodymium-doped crystals in a heralded fashion. I will then show how polarization qubits encoded in true single photons can be stored in such crystals, despite their intrinsic birefringence and polarization-dependant absorption. I will finally present an on-demand quantum memory exploiting the long hyperfine coherence time of europium ions to store light for up to 8 ms. Our results highlight the great potential of REIC for quantum repeaters.