Gmunden
Graz
Innsbruck
Linz
Mölltaler
Pitztaler Glacier
Postlingberg
Salzburg
Serfaus
Vienna (Wien)

Photo courtesy Gerald Kempel
Salzburg
LRT subway
 
Salzburg has a local interurban with it's main terminus underground. According to Josh Hanz (thanks Josh!), "If and when the Lokalbahn line is extended to the Kapuziner (near Mozart's birth house) it will be a real subway."  However, there are plans.

Trams disappeared from Salzburg streets 60 uears ago, and even included usage of a small tram tunnel built in the 1700's.