Fluctuations in de Sitter space
Cosmologist Sean Carroll has proposed that low entropy may result from fluctuations in De Sitter space - a vacuum except for dark energy and the end point of expanding space time. Some fluctuations lead to cosmological inflation, giving rise to smooth low entropy 'baby universes' - like ours.
This theory is a variation of the inflationary universe theory. However its authors claim that it addresses the key weakness of the latter as an explanation of initial low entropy and the arrow of time: the fact it presupposes an area of low-entropy dark energy. The multiverse theory gives an account of how such areas could arise from fluctuations in empty (de Sitter) space (note Explanation cross link). The theory also implies that the multiverse as a whole will be time-symmetric, with the arrow of time pointing in opposite directions in roughly equal numbers of universes.
The excerpt from the paper co-authored with Jennifer Chen (cited below) makes clear the appropriateness of grouping this with the arguments that appeal to anthropic selection.