This addon was originally
programmed by Campbell Barton some years ago for the Apricot project.
I updated it to the new Python API.
It does reducing of polys, keeping face loops, it works as an "unsubsurf"
Documentation
First go to User Preferences->Addons and enable the PolyRedux addon in
the Mesh category.
Select some elements and invoke the addon (button in the Tool panel).
The selected area will be polyreduced.
If you wish to hotkey PolyRedux:
In the Input section of User Preferences at the bottom of the 3D View >
Mesh section click 'Add New' button.
In the Operator Identifier box put 'mesh.polyredux'.
Assign a hotkey.
Save as Default (Optional).