Vein-O-Vision

I see you, a thief on the roof. My new satellite link has both infrared and the x-ray spectrum. I see your heart beating. I see you are afraid.

—Gunther Hermann, Deus Ex

Predators develop senses that help them hunt. Sharp sight, delicate hearing, a keen nose... and Vein-O-Vision. Dracula and his ilk, as well as weirder fare, will have among their Super Senses the ability to see all the major and minor blood flows in a human body, often going to near X-Ray Vision levels by seeing their dinner's still beating heart!

This is something of a subconscious power, usually triggered by hunger. Vein-o-vision may be noticeable to onlookers if the character also manifests Animal Eyes, but otherwise the power is inconspicuous. A Vampire Refugee or Friendly Neighborhood Vampire will probably have to use Heroic Resolve to resist sucking on so many delicious veins in plain view. As such, this can cause a Tomato in the Mirror or similar effect on a character once they realize their best friend is now on the dinner menu.

Also in a pinch, makes the stalking vampires' POV sequence all the creepier, showing us just how much of a Happy Meal the hero is to them.

Compare Meat-O-Vision. Contrast Volcanic Veins and Tainted Veins. See also The Dead Have Eyes.

Examples of Vein-O-Vision include:

Anime and Manga

The Chakra lines seen by the Byuakugan in Naruto look like this.
- In addition, the technique itself makes its user's eyes rather ...veiny.
In Vampire Hunter D, Meyer Link gets from time to time when he looks at Charlotte Elbourne, his human lover.
In Vampire Knight, we see that Yuki, and thus probably all other vampires, can detect blood flows.
Grappler Baki's Hanma Yuujiro can see, or feel, or just perceive the flaws in everyone's body. So he is able to predict diseases and attack the weak points of any living being.

Film

Used in Night Watch as the main character watches a boy while a vampire.
The not at all friendly vampires in Van Helsing have this power.
Appears for a brief moment in Francis Ford Coppola's Bram Stokers Dracula.
This is how vampires see people in in Vampire Girl vs. Frankenstein Girl.
The mad scientist in the film version of From Beyond, having acquired Horror Hunger after his peek into another dimension, has flashes of Brain-O-Vision, seeing through people's skulls to the gray matter he craves.

Literature

Part of the fake, made-up, not-to-be-taken-for-real Karmic Twist Ending in Roald Dahl's The Wonderful Story of Henry Sugar.
Howlers were mentioned as being able to see their enemies' "weak points", such as blood vessels, in Animorphs.
Genevieve from the Warhammer Fantasy Battle novels has this ability.
Salacia von Humperding in the Discworld novel Thud!:

"I can count fifty-seven hearts beating," said Sally.
Angua gave her a Look. "You know, that's one particular talent I'd keep to myself, if I were you."

- All of the vampires on the Discworld have this ability. The only living things they can't detect are any of the various species of the Troll family. (Or is it Genus?)
Similarly, heart hounds in The Sword of Truth series hone in on the sound of their prey's heartbeat.
Shows up in Anita Blake a lot, with a bit of synaesthesia (nothing supernatural is described in pure sensory terms). Anita tends to perceive the veins as leaping out of the skin, begging her to tear their owner's throat out and free them from their prison. (She's not actually a vampire, but...)

Live-Action TV

The Monster of the Week in the Supernatural episode "Metamorphosis", a man whose transformation into a monster will be completed by his first bite of human flesh, experiences this after his wife cuts herself. He flees to avoid hurting her.
Hungry vampires get this in Moonlight. Mick, a Friendly Neighborhood Vampire, does this when trapped in a desert with the only human being around a pregnant girl.

Tabletop Games

The Dungeons and Dragons third edition supplement Complete Scoundrel offers the spell "Healer's Vision," which is usable by two classes. Clerics who cast it can heal the target better because injuries become easier to see; Assassins can make use of it because being able to see your target's organs takes the guesswork out of where to stab them.

Video Games

In The Witcher 2: Assassins of Kings, Geralt can get Vein-O-Vision, as well as night vision, by drinking a Cat potion.
One of Jericho's main powers in Darkwatch.

Web Comics

Layla from Eerie Cuties approached Chloe about an earlier biting... before finishing her dinner... and remembered that incident. Thus, we got this.
Vein-O-Vision appears a few times in The Kingfisher.

Western Animation

The Batman vs. Dracula

Real Life

Truth in Television: Vampire bats have a limited thermographic sense, allowing them to select the best places to bite. They're not actually looking for veins to penetrate, but for areas where skin is thin enough to bleed easily. Given that such bats' usual prey (livestock or poultry) are thicker-skinned than humans, this is a handy sense to have.
Mosquitoes also uses some sort of a thermal imaging to detect nearest vein to the skin.
Various "vein viewer" or "vein vision" devices, largely based on principles of transillumination, claim to allow medical providers to "see" deep peripheral veins for intravenous access. This can be a handy trick in an emergency, or if you need an IV on someone with poor surface veins. Unfortunately the devices rarely work as advertised - a skilled phlebotomist can do just as well or better without the device, and the devices occasionally fail to visualize surface veins that can easily be seen with a naked eye.