  We discuss the phase diagram and the universal scaling functions of
attractive Fermi gases at finite imbalance. The existence of a quantum
multicritical point for the unitary gas at vanishing chemical potential $\mu$
and effective magnetic field $h$, first discussed by Nikoli\'{c} and Sachdev,
gives rise to three different phase diagrams, depending on whether the inverse
scattering length $1/a$ is negative, positive or zero. Within a Luttinger-Ward
formalism, the phase diagram and pressure of the unitary gas is calculated as a
function of the dimensionless scaling variables $T/\mu$ and $h/\mu$. The
results indicate that beyond the Clogston-Chandrasekhar limit at
$(h/\mu)_c\simeq 1.09$, the unitary gas exhibits an inhomogeneous superfluid
phase with FFLO order that can reach critical temperatures near unitarity of
$\simeq 0.03\, T_F$.
