Good things: If you like the Olympics, they run the live feed on Televisión Española for twelve hours, and then they re-run the whole thing at night. All the big events are televised live in prime time, since Spain is just one hour off Greenwich Time.
Bad things: If you thought the Americans were nationalists, wait until you hear the Spanish announcers openly cheering on their female water-polo players, clapping and yelling "Bravo, Malena, vamos!" Any event a Spaniard might medal in is given first priority; then any event that a Spaniard is participating in. This means lots of sailing and women's judo and men's beach volleyball and men's field hockey. There is open rooting against well-known foreign athletes, hoping to see them taken down a peg.
Right now they're obnoxiously cheering on the men's water-polo team against Kazakhstan. No kidding. "Let´s go, come on, Felipe, goal! Goal! Goal! Spain completely outclassing the Kazakhs!"
The funniest bit of sports nationalism was a couple of Winter Olympics ago when this German cross-country skiing star named Johan Muhlegg got mad at the coach and changed his nationality to Spanish in revenge. He then proceeded to win three golds, about the first ever won by Spain at the Winter Games, and there were articles in the papers saying "He may not speak Spanish, but his heart is as Spanish as any of ours." Then he got busted for doping and stripped of his medals and no one has heard of him since.