Once an obscure skill practiced by a handful of baristas, latte art is invading the home. Amateur artists have posted thousands of photos and videos of leaves, flowers and swans made in foam, on Web sites like YouTube, Rate My Rosetta and CoffeeGeek.

Coffee shops offer classes in creating designs, and latte artists organize winner-take-all cash contests, or "throw downs," in which amateurs challenge each other, as well as local professionals. Espresso-machine vendors are doing a brisk business in special pitchers and custom steam tips that are affixed to machines to aid milk frothing. One online retailer says sales of its $79 "Latte Art Beginner's Pack," with instructional DVD, frothing pitcher and milk thermometer, are up 65% this year.

The pastime is not for those with weak wills -- or shallow pockets. High-end home espresso machines sell for as much as $7,000. Beginners can go through multiple gallons of milk a week as they practice.

Some aspiring artists concentrate on the pour. First-timers mistakenly think they can paint the design on top of the coffee, says Nicholas Lundgaard, a 23-year-old software engineer in Houston, who took up latte art three years ago after seeing photos on the CoffeeGeek Web site. Actually, it's "a fluid canvas, where shapes fan out from the place you're pouring," he says.

Mr. Lundgaard spent evenings hunched over his espresso machine, studying exemplars on YouTube and rehearsing his "wiggle," the back and forth motion of the hand pouring milk. To avoid wasting costly milk, Mr. Lundgaard practiced with water, switching to milk every now and then to gauge his progress.

Another foam artist, Milwaukee pathologist Robert Hall, says he had to pour five or six drinks a day for a year before he could get a rosetta right every time. One big obstacle was his wife's preference for skim milk, which produces stiffer, less yielding foam than milk with lots of fat, he says.

Not everyone wants to suffer for their art. After seeing a latte-art video, Oleksiy Pikalo, a 31-year-old electrical engineer from Somerville, Mass., decided there had to be an "engineering approach." Using a kit and spare parts found on eBay, he built a programmable computer printer that stamps designs -- such as words or corporate logos -- on foamed drinks in edible brown ink. One design shows a kingly figure saying, "Can your latte do this?"

Mr. Pikalo presented his invention at a national computer-graphics conference this week and has started a company, OnLatte, to sell his machine, at a tentative price of $1,500. His YouTube video has drawn more than 818,000 views and 2,500 comments.

After the museum we're out on the street looking for our next destination. Suddenly my wife grabs my arm and Tiger Lilly gasps audibly and freezes. What? Did some threat get past my radar? My wife directs my attention to the opposite corner of the intersection and I see that we may indeed be in line for a mugging. It's American Girl Place.

A year ago I had no idea of the marketing volcano that was about to erupt under our feet. Then some black-hearted scoundrel slipped Daughter Two an American Girl catalog - the first one's free, kid - and her life changed. American Girl dolls are a vertically integrated economic powerhouse. The dolls themselves go for nearly $100 a pop, but that’s just the threshold - the dolls represent different eras and ethnicities in American history and most are the stars of one or more books put out by the company and has full line of accessories, not to mention the magazine (catalog) that appears regularly at our house. My daughter and her friends now can recite model numbers, back stories and accessory details with each other the way my friends and I once were able to argue the finer points of a '63 Impala or '67 GTO.

When Tiger Lilly picked her favorite from the catalog - an American Indian called Kaya - we said that if it was that important to her she would have to earn the money herself. A born entrepreneur she quickly grasped the profit and loss mechanics of a lemon-aid stand and the economic rewards of an untapped market - extra chores - to build liquidity. With a seed loan from Mom she bought lemons and sugar, and with marketing advice from me ("put 'Fresh Squeezed' in big letters on your sign"), along with her natural charm and location, location, location she quickly covered her start-up costs and had money to plow back into her business as well as show a profit. This was repeated a couple of more times, and along with the household moonlighting she soon had the necessary discretionary income to buy her doll.

And now we were unwittingly across the street from Mordor, I mean, American Girl Place. It was like setting out for Oz and finding Mecca along the way. I looked around and saw a definite flow of young girls, many with dolls in arms and all with parents bobbing in tow, converging on the store from all directions. We were swept up in the current - as if we ever had a choice - and into the store. The store is impressive in both detail and scope, with three floors of merchandise and a restaurant where you can have lunch with your American Girl doll for just $22 per person. If I’m going to spend that much for lunch with a doll, I want to see the doll cook the meal and then serve it and then give me a quote on painting my garage. Nevertheless the store is jammed on every floor and countless cashiers and floor associates are - like everyone else in New York - working hard. Fortunately there were no meltdowns to be observed such as those we'd witnessed at Toys R Us in Times Square the night before, but I did notice a lot of earnest young faces making a case point by point. After Tiger Lilly parted with more of her profits she'd been saving for this trip we went elsewhere for lunch (Kaya would just die if she knew we’d eaten at American Girl Place without her) and then, since it had stopped raining, we went over to the Central Park Zoo.

We arrive just in time for the Polar Bear feeding and to see another New York career option - bear feeder. At this zoo they feed the Polar Bears by first luring them out of the habitat enclosure and into their dens where they can presumably be locked up. Once that is accomplished a zookeeper enters the habitat and hides buckets of food - fish, apples and some veggies frozen in a block and smeared with peanut butter - in the enclosure. While we’re watching this preparation we speculate that there’s probably some initiation for rookie keepers where, once they’re in the middle of the enclosure with bear chow and an open jar of peanut butter, someone plays a loud recording of a Polar Bear huffing and roaring.