Some of television's top programs with violence or surgery as key ingredients have all but elevated blood to honorary character status.

These shows, including CBS's CSI, Fox's 24, HBO's The Sopranos and Six Feet Under, NBC's ER -- and newest entry, FX's Nip/Tuck -- rely heavily on technical savvy to generate red stuff so realistic that audiences keep coming back for more.

"Years ago, there wasn't a big blood selection, but today you have your choice of dark and light blood gels, flowing blood, arterial blood and venous blood," says CSI head of make-up effects John Goodwin (search). "On CSI we use dried blood a lot. Blood really does change color when it dries -it's much browner."

In the era of black and white television, creating blood f/x was a lot simpler.

"They used chocolate syrup," said Goodwin, who adds that back then, when simulating blood, one could do "practically anything, as long as it had the right consistency."

These days, Goodwin relies on his technical advisors to know what the different bloods look like, but concedes he must make certain adjustments.

"A lot of the blood is a little redder, a little more orange than it should be, just so it reads correctly on film," he said.

Technology continues to impress. Says Goodwin: "It seems like every day there's a new visual effect we can do that the computer people come up with."

Although he acknowledges the "morbid curiosity in each of us," Goodwin is no fan of gratuitous splatter.

"I like to think the show is plot-oriented and that blood is just part of the story-telling," he says.

When viewers separate these elements in favor of the blood, the results, he suggests, can become a "peep show."

Edward T. McAvoy (search), Nip/Tuck's production designer, says his program's focus on blood actually ties into an even more serious agenda.

"One of the things we're doing is looking into the world of why people are so unhappy with themselves that they're willing to undergo plastic surgery," McAvoy said, explaining that the ultra-real look of the blood is meant to provoke people to ask themselves if they really want to do this to their bodies. "Plastic surgery is major surgery and people actually die from it."

While he lightheartedly refers to his technical expert, nurse Linda Klein, as the "arbiter of blood" ("It takes someone who's seen the real thing to recreate it," he says), McAvoy knows where displaying blood graphically may lead.

"There's a darker side of me that, to some degree, thinks we're pushing the envelope of sensationalism in order to grab viewers," he said. "It's like, 'Ooh, this is awful, I don't want to look but I can't stop looking.'

"The filmmaker side of me agrees wholeheartedly with Hitchcock -- imply violence, don't show it."

Not surprisingly, McAvoy rates the shower scene in Hitchcock's Psycho as the most riveting use of blood. "The only blood you saw, which was so minimal, was what was washing down the drain," he said. "In everybody's mind, that stands out as one of the most gruesome scenes ever filmed but, if you analyze it frame for frame, what's gruesome is what's going on in your imagination."