MultiLayout is a theme with minimal styling which enables various 1, 2 or 3 column page layouts to be used from within the single layout file with little recoding (one line to be uncommented). It is intended to be used as a parent theme for further styling (in the same manner as Base/Standard) rather than as a complete site theme on its own. The GitHub link below will download both multilayout and a child theme 'multistyled' which extends the parent theme with a settings page and colour scheme.
Alongside the multiple layouts, it also has additional block regions above and below main content to provide maximum flexibility for the layout of any page.
Multilayout is based on Matthew James Taylor's stacked columns layouts here