Cats take over the Internet -- What is it about our feline friends that keeps us glued to our YouTube?

She’s bigger than Megan Fox. Hotter than Hayden Panettiere. More downloaded than Jessica Alba. She’s one of the most clicked-on females in Internet history. Her name is Nora. And she’s a 5-year-old tabby who can play the piano.

In the universe of online cat videos — and that’s a much, much larger universe than many dog lovers might suspect — Nora is a superstar. Her piano performances have been viewed nearly 20 million times since they first started popping up on YouTube two years ago. She has her own calendar, a DVD of her recitals, and two books for sale on Amazon (Nora the Piano Cat’s Guide to Becoming a Good Musician and My Story: A Picture Book). Earlier this summer, a composer in Lithuania incorporated one of Nora’s compositions into a ”CATcerto” with an 18-piece orchestra in front of an audience of 600 people. (A video was posted on YouTube last month.) ”It’s nuts,” says Nora’s owner, Betsy Alexander, a piano teacher in Pennsylvania for 30 years. ”Nora’s got an agent.”

As it happens, Nora isn’t the only feline becoming famous online. There’s also Gizmo, the cat who repeatedly — and hilariously — flushes a toilet (4.8 million hits). And Maru, an adorable bundle of fur from Japan who appears in a series of videos diving into cardboard cartons and getting his head stuck in paper bags (as many as 4.2 million hits). There’s the kitten who eats broccoli, the cat who jumps onto a baby, the one who stalks like a ninja, and another who chases away a bear — all of them being clicked on (and e-mailed to friends) thousands of times every day.

In fact, so many eyeballs are glued to so many cat videos, it’s fair to say they’ve become a full-blown pop culture craze. There aren’t any awards shows for them yet, and they don’t get reviewed by national magazines (until now; see sidebar), but cat videos are becoming as much a part of some people’s daily entertainment diet as the TV programs they record on their DVRs or the books they download to their Kindles. And it’s not just videos. There are websites devoted to cat photography, like the Lolcats of (where pet owners post pictures of their kitties with punchlines like ”Help the blanket gotz me”), and, which features photos of cats that amusingly resemble the Führer (for cats that look like Wilford Brimley, you have to go to Yes, there’s even a cat on Twitter, Sockington, who recently passed the half-million-followers milestone with tweets like ”pad pad pad pad pad pad pad pad pad pad pad pad pad pad pad pad pad what oh NOTHING pad pad pad pad pad pad pad pad pad.” Snoop Dogg has only 370,000 followers on Twitter.

Animal acts are nothing new in entertainment. David Letterman has been showcasing Stupid Pet Tricks for decades. And movies about animals have always been crowd-pleasers (last year Marley & Me grossed $143 million, without a single cat in it). There’s even a whole cable network devoted to our four-legged friends, Animal Planet, which sometimes gets ratings as good as the cable news channels. Pets in general are a mega-industry in the U.S., with Americans spending an estimated $43 billion a year. And yet, as with everything on the Internet, nobody has figured out how to make money from cat videos. ”The videos that are taking off and becoming viral aren’t really professional — they’re a guy with a camera and a cat,” notes Tracey Paull, digital-media director at Spark Communications, a media agency in Chicago. ”That’s a really hard thing to monetize.”