A pedestrian refuge island was installed at the corner of Seventh and Washington in Ann Arbor in order to make it easier for pedestrians to cross busy Seventh St at that corner. The City of Ann Arbor project page details the construction effort.
Between the time of its installation in October 2009 and February 6, 2010, the sign at that island was replaced 11 times due to car-sign collisions. An AnnArbor.com story of Feb 3, 2010 has some details, and the Ann Arbor Chronicle's "Stopped Watched" column has more.
A webcam watches vigilantly over the sign, with a corresponding blog that tracks the periodic car-sign accidents and the city's responses.