I just happened to see a fan vid for Remington Steele today and that might qualify.

As it happens I just saw a crossover scene on Moonlighting for Hart to Hart. I never watched that show but I wonder now if I would like it. Anyone seen it?

I also haven't seen Queer as Folk (US) in some time but it surprises me it isn't a show that is referenced more often given what a landmark it was.