A not so simple layout that attempts to put all windows in a square grid while obeying their size hints.

You can use this module with the following in your ~/.xmonad/xmonad.hs:

 import XMonad.Layout.HintedGrid

Then edit your layoutHook by adding the Grid layout:

 myLayout = Grid False ||| Full ||| etc..
 main = xmonad defaultConfig { layoutHook = myLayout }

You can also specify an aspect ratio for Grid to strive for with the GridRatio constructor:

 myLayout = GridRatio (4/3) False ||| etc.

For more detailed instructions on editing the layoutHook see XMonad.Doc.Extending.