Associated Press list of recent HEMS accidents; I don't believe the list is complete, because no 2007 accidents are listed.
According to FCC data, the tower hit last week in Aurora (WBIG-AM) was in a
three-tower array. I have often seen such arrays with one or more towers completely dark. The "lights out" issue isn't just a concern among pilots;
Radio World magazine has also highlighted the issue, notiing the unresponsivenes of both FCC and FAA. When one or more lights are out, and can't be quickly fixed (due to wx or whatever), a competent owner will try to alert FAA to issue a NOTAM. But they often run into bureaucracy; "That office is in Minot...".
However, the pilot was close to his home base in Bolingbrook, and familiar with the towers as a landmark.