  We present an overview of recent developments in species-imbalanced
("polarized") Feshbach-resonant Fermi gases. We summarize the current status of
thermodynamics of these systems in terms of a phase diagram as a function of
the Feshbach resonance detuning, polarization and temperature. We review
instabilities of the s-wave superfluidity across the BEC-BCS crossover to phase
separation, FFLO states, polarized molecular superfluidity and the normal
state, driven by the species imbalance. We discuss different models and
approximations of this system and compare their predictions to current
experiments.
