For Betsy Alexander - dumpster diver and found-object artist - the gray tabby she rescued from a Cherry Hill shelter and named after a surrealist painter is proving to be her most celebrated pick.

You might know her discovery as Nora, the piano-playing cat. Eleven million views on YouTube and climbing.

Alexander and her husband, the artist Burnell Yow!, realized one night three years ago they had a feline phenom. They were upstairs in their rowhouse/studio on Naudain Street in Center City. Nora - named for Leonora Carrington - was downstairs in the music room.

Suddenly they heard the piano, the same note repeated over and over.

"It was the weirdest thing," Alexander recalls. She thought: "Are we haunted?"

No, just charmed. They descended the stairs to find Nora sitting on the piano bench, her right paw hammering the Yamaha Disklavier.

"We stood there, astonished. She looked up at us, and I imagine her look said, 'What?' Then she went right back to what she was doing."

Nora became an immediate hit among many of Alexander's piano students. Two grands sit side-by-side in the music room, and sometimes, as students played their Bach and Beethoven, Nora accompanied them on the spare keyboard. (For those few students annoyed by the feline's playing, Alexander would move the piano bench back a foot or two. Nora won't play if she can't sit properly.)

A star is born

One day last January, Alexander's students suggested she make a video of Nora and post it on YouTube. Alexander didn't have a video camera. She'd never heard of YouTube.

But thinking that her niece in Wyoming would get a kick out of seeing Nora in action, Alexander got her husband, who designs Web sites, to post the two-minute, 48-second video of Nora playing with one paw, two paws, reaching for the black keys then accompanying a student on Bach's "Minuet in G," in a sort of primitive, cat way.

The couple called the video, Nora: Practice Makes Purr-fect and by the end of the first day, 71 people had found the video.

Says Alexander: "We were like, 'Who are these people?' "

The next day Nora got a couple hundred hits. She was an Internet sensation. The Alexanders, who have spent decades seeking audiences for their art, were dumbfounded.

Since then, Nora has graduated from local news to the big time. Martha Stewart sent a little bust of Bach. Billy Joel sent a photograph to the piano cat from the Piano Man. Bookers from Leno and Letterman have called.

Nora doesn't travel

Traveling to New York for TV appearances was out of the question, Alexander informed producers. Being a cat, Nora is too easily distracted, and unlikely to play on demand.

So the media beat a path to her door - The Today Show, VH1, Japanese TV, the BBC.

The Beeb sent an animal behaviorist to observe Nora, her piano playing and her relationship with the five other cats in the house, and came away convinced of something that happens to a lot of creatures with skills.

The other cats resent her.

Particularly now that she's been voted a finalist in the YouTube Awards. She lost last month to a laughing baby.

A trip to Nora's house is a trip indeed. Alexander and Yow! have stuffed the place with found objects repurposed for posterity - toasters and spoons and rakes and Sprite cans fashioned into modern art.

When I walked in, Nora was at the piano, sitting on the leather seat, her paws resting together on the white keys. She was silent for the longest time, as Alexander, 52, shared what the behaviorist had said about her cat.

Nora wanted to be dominant from the start, Alexander said, which is why as a kitten she got into a lot of fights. Noticing that the other cats slept upstairs during the day, Nora started hanging out during piano lessons and realized that those who played earned Alexander's attention. "Obviously, it worked," Alexander said.

The way Nora rests her head on the keys when she plays suggests she's sensitive to the vibrations. She also could be marking territory. "It's like the piano has become Nora's giant personal cat toy," Alexander says.

With that, Nora played a jagged, four-note burst - the sort one might hear on an episode of The Twilight Zone to accent a moment of eerie import.

Cat can play.

Contact Daniel Rubin at drubin@phillynews.com or 215-854-5917