A research team led by Martin Lockley and Karen Houck of the University of Colorado Denver have found new evidence for courtship behavior in theropod dinosaurs. According to Lockley et al, "scraping" traces associated with theropod footprints are morphologically similar to those left by modern ground-nesting birds in leks. If the behavior was indeed similar, then we can add courtship displays to the ever-growing list of similarities between avian and non-avian dinosaurs.
The relevant paper can be found here.