Online Extra: Marketers, Don't Call Them "Seniors"  This year,
about half of the 77 million members of the baby boom generation
will be age 50 or older. In the marketing business, age 50 has
traditionally been the age at which a consumer's value to mass
marketers plummets. But boomers, with their vast numbers,
unprecedented wealth and life expectancy, and surprisingly
energetic lifestyles, present a huge business opportunity to
marketers ranging from consumer-products and clothing companies
to auto makers and food companies.  BusinessWeek Correspondent
Louise Lee spoke with Matt Thornhill, president of The Boomer
Project, a marketing consulting firm based in Richmond, Va.,
about Corporate America's changing attitudes toward the middle-
aged consumers. Edited excerpts follow:  Why is the boomer
generation in danger of falling off the marketing radar screen?
Boomers have aged themselves out of the traditional sweet spot
of ages 18 to 49. As boomers aged, advertisers and marketers
started to ignore them. Now, adv