Dick Wolf is the creator of Law & Order.  Michael Imperioli was an actor in several episodes.  In the Sopranos, Christopher mentions Dick Wolf a lot after he gets into the movie business.  Don't know how many instances and what content or context.  Just about the entire cast of the Sopranos also played on earlier episodes of Law & Order, before Sopranos came out in 1997/8 (?).  Everybody but Tony from Sopranos did at least one episode of Law & Order before Sopranos came out.  I just think that's amazing.  I'd really like to learn more about this.  Do the creators of each show know each other, or knew each other before Sopranos was created, at least?