The Internet can be the worst kind of one-night stand, loving you today and dumping you tomorrow.

I was reminded of that over the weekend when I went to Office Max for some printer paper. I noticed a small sign promoting www.elfyourself.com, the Office Max site that lets you paste a photo of your head onto the body of a dancing elf. My first thought was, "Does that site even exist anymore?"

Actually, it does, but last year's must-visit holiday site is a shadow of its former self. According to compete.com, ElfYourself got about 450,000 visitors in the last month. Sounds like great traffic — and really, it is. But consider that the same site got more than 25 million visitors last December.

White-hot a year ago, down 98 percent today. What have you done for me lately?

Building lasting brand equity on the Web isn't easy. Every day brings a new Web sensation, and the burn rate is enormous. Plus, much of what takes off on the Internet isn't easily linked to a brand or product.

Flavors of the day
In recent months, Web flavors of the day have included the Hong Kong "bus uncle" rant; free downloads of Suze Orman's "Women & Money" book; various puppy-cams; the Montauk sea monster; and raunchy video parodies like "D*** in a Box" and "I'm F***ing Matt Damon." You could make your own list with dozens more.

But what do you do with this jumble to link it in a memorable and meaningful way to a product?

You can't, really. Sure, NBC has gotten traction for Hulu.com by posting memorable "Saturday Night Live" sketches there. The publicity and word of mouth for Orman's free download probably helped drive paid sales of her book. (It also didn't hurt that it was sponsored by Oprah.)

But the smartest way to build lasting brand equity on the Web is to engage your customers consistently in ways that are enjoyable for them and generate insights for you.

One good example is under way right now by Purina, which is doing some promotional tie-ins with the movie "Marley & Me," opening on Christmas Day. At LongLiveYourDog.com, Purina asked users to post videos of their dogs' rascally antics. The winner gets a trip to Hollywood for the movie premiere.

The site also hosts a series of "Dog Park Hall of Fame" videos, as well as information on dog health, nutrition and care — along with Purina product information, of course. Traffic, though not overwhelming, has grown steadily. At 45,000 visitors a month, it's up more than 50 percent over the past year.

In an earlier post, I wrote about Kraftfoods.com, which attracts millions of visitors a month with its unspectacular menu of food tips, recipes and forums. These are the kind of committed, well-planned offerings that are likely to build long-term consumer loyalty.

I've heard firsthand from some large companies that aren't interested in having two-way communication with their consumers through social media. They consider feedback to be a customer-service function, and so they farm it out to phone banks. Under this model, the consumer is a pain in the ass to be shunted aside, rather than a partner with potentially valuable information to share.

That's a mistake, in my view. Those companies are missing out on communication with their customers that could yield valuable insights into what motivates buying decisions and brand loyalty.

Also keep in mind that as the traditional media continue their struggles, they'll be less willing and able to tell company stories in their pages and on their airwaves.

Companies that wish to communicate with the buying public increasingly will have no choice but to step up and do it themselves.