  From considering the effect of gamma-gamma interactions on recently observed
TeV gamma-ray spectra, improved limits are set to the density of extragalactic
infrared (IR) photons which are robust and essentially model-independent. The
resulting limits are up to two orders of magnitude more restrictive than direct
observations in the 0.025-0.3eV regime. These limits are used to improve
constraints on radiative neutrino decay in the mass range above 0.05eV and on
Very Massive Objects (VMOs) as providing the dark matter needed to explain
galaxy rotation curves.
