Living on the edge: Cosmology at the edge of anti de Sitter space

String theory, which is supposed to be the fundamental theory of quantum gravity, has now mutated into membrane theory (brane theory), and given rise to some peculiar cosmological models called "brane cosmologies".
In these models our entire observable universe is supposed to be a (3+1)-dimensional membrane embedded in a higher dimensional (9+1)-dimensional fundamental reality. I'll try to explain why these models are considered so attractive by the particle physics community (several hundred papers have already been written), and how they might reasonably impact on the astrophysics community -- there are potentially observable consequences, both in the early universe and in precision laboratory experiments.