Effectively, in Windows 8 the Task Manager's Applications tab has lost its Windows menu. Just another useful option lost in Microsoft's course for Metro.
You can still right-click on an empty Taskbar area and choose "Show Windows Side by Side". I don't know if Windows 8 has kept the other options of Cascade and Stacked. As these options work on all the windows, they might do too much for you.
As usual, when Microsoft subtracts, one is obliged to fill the hole with third-party products. Here are some products that rearrange windows on the desktop (although I don't know how well they work in Windows 8):
WindowSlider
Plumb
GridMove - not exactly what you ask for, but still a very interesting concept.