Serrano ham is the obvious essential, but bear in mind that there are various qualities, usually based on the length of curing. Jamón Ibérico is from the indigenous black pig and the very best is bellota, acorn-fed. If you have the ability and confidence, you can buy a piece or a whole leg, otherwise it is available sliced.
Other meats include chorizo, salchichón, the equivalent of salami, and lomo which is cured pork loin. There are, of course, regional specialities including fuet from Catalonia, and varia and camaiot from Mallorca, but they are rarely found outside Spain.