  Recent work has uncovered Schottky-like peaks in the temperature dependence
of key specific heats of certain black hole thermodynamic systems. They signal
a finite window of available energy states for the underlying microscopic
degrees of freedom. This paper reports on new families of peaks, found for the
Kerr and Reissner-Nordstrom black holes in a spacetime with positive
cosmological constant. It is known that a system with a highest energy, when
coupled to two distinct heat baths, can naturally generate a thermodynamic
instability, population inversion, a channel for work output. It is noted that
these features are all present for de Sitter black holes. It is shown that
there are trajectories in parameter space where they behave as generalized
masers, operating as continuous heat engines, doing work by shedding angular
momentum. It is suggested that bounds on efficiency due to the second law of
thermodynamics for general de Sitter black hole solutions could provide
powerful consistency checks.
