Culatello ham is a high-quality cured pork product similar to (but experts say better than) prosciutto. This specialty ham uses the rear muscle mass from the leg of the pig. The best product is said to be Zibello culatello, air-cured and traditionally aged in 500 year old caves. The ham is slightly dryer than Prosciutto.
You can read about the process of producing this specialty ham here. You can also see a National Geographic video of how the Culatello ham is produced here.
Like prosciutto this ham should be sliced very thin. You can serve it as part of a charcuterie plate with Parmesan cheese or eat it in a sandwich with crusty Italian bread.
You may not find real Italian Culatello in your local deli. You can certainly purchase it online at Parmashop.com. Also, chef Mario Batalia's father makes a Culatello in Seattle using traditional methods. You can purchase it Salumicuredmeats.com.