  We review recent progresses in the study of factorized resonance scattering
S-matrices. The resonance amplitudes are introduced through a suitable
analytical continuation of the ADE Toda S-matrices. By using the thermodynamic
Bethe ansatz approach we are able to compute the ground state energy, which
describes a rich pattern of flows interpolating between the central charges of
the coset models based on the ADE Lie algebras. We also present the simplest
resonance ``$\phi^3$'' scattering model and discuss its relation with new flows
in non-unitary minimal models. Further generalizations are discussed in terms
of certain asymptotic conditions in a family of ``resonance'' functional
hierarchies.
