My wife's parents' family names are Ungurean and Roman. Another important ancestral name is Marginean. Her ancestors come from the area of Tau. On our last trip to Romania, we found a map of judetul Tarnava-mica from 1930, which is where Tau was then. It was the first time my wife had ever seen Tau on a map. Unbelievably, nowadays you can simply link there with an interactive map at http://www.calle.com/world/RO/0/Tau.html or at Mapquest!
More information will be posted as time progresses, but any input about the history of Tau is welcome!