DPR Model Slicer is a free Revit plug-in which facilitates the creation of 3D Building sections from a Revit model. Inherently within Revit, the only way to separate a model by floor is to filter it by reference levels. Unfortunately, this often results in a product (shown below), where items modeled as multi-floor elements, such as walls or columns, become associated with only one floor despite occupying space on many floors.
During the construction coordination process, this can be a limitation, so it is often desired to have the building model separated into individual floors. DPR Model Slicer makes this process faster. The end result is a model which is sectioned by floors.
More information on DPR Model Slicer here.
Thanks to Clay Hickling of GHD and his presentation at the Revit Technology Conference USA 2011, "10 Free Revit Add-ins You can't Live Without"