  We study fluctuating two-charge supertubes in three-charge geometries. We
show that the entropy of these supertubes is determined by their
locally-defined effective charges, which differ from their asymptotic charges
by terms proportional to the background magnetic fields. When supertubes are
placed in deep, scaling microstate solutions, these effective charges can
become very large, leading to a much larger entropy than one naively would
expect. Since fluctuating supertubes source smooth geometries in certain
duality frames, we propose that such an entropy enhancement mechanism might
lead to a black-hole like entropy coming entirely from configurations that are
smooth and horizonless in the regime of parameters where the classical black
hole exists.
