My 'pet wish' application for Windows 8 that's along the lines of the sort of thing Stardock does best would be a more fully functional TWM or Tiling Window Manager for the Metro/Modern/NCI interface.  While Microsoft has set app standards for the limited two application split at roughly 33:66, this was developed for low resolution hand held and tablet displays; on the desktop with larger screens and aspect ratios much more utility can be had where a 50:50 split would be completely practical -- as more then just two applications can easily be displayed at higher resolutions if the split metrics are configurable, and it doesn't have to be confined to a simplistic side-by-side layout...

As well the Windows 8 compositor allows for tiling and even windowing the 'Desktop' with fully dynamic resolutions -- which again could allow for raising the bar of utility in using Desktop and 'Modern' applications concurrently substantially if the 33:66 two pane barrier is broken.

Last, but far from least, in fact probably the most important is the control interface for the Modern TWM was built for a touch screen and is abysmal on the Desktop, with scroll bars, finicky hot corners, a Charms Bar that switches you 'out' of being able to multi-task while using any charms 'features', and awkward drag scheme to tile -- this is the complete opposite of what good TWM design achieves on the Linux OS for Desktop where substantially less User manipulation of the interface is required then a CWM (Cascading Window Manager) paradigm to get the same thing done.

Obviously Stardock or any Developer for that matter may not be address all these issues and limitations, as there's no API to control some features, and work-arounds and hacks are bound to give unsatisfactory results -- but there's plenty of ground floor opportunity here for adding real form that follows function and value to the OS that Users won't want to be without.