St. Sabina's is close to the headquarters of the Knights of Malta. A body of Knights were seated at the front of the congregation in their Maltese cross-emblazoned cloaks, (the original "blazer"?). Apparently, the faithful who process to this church for Ash Wednesday may gain special indulgences.
The basilica is also notable for its original carved cypress door panels, one of which is the earliest known depiction, (430 AD), of the Crucifixion of Jesus.
The "door panels" link is from Sacred Destinations, which has another great article on St. Sabina's, and a nice gallery of photos.