Big companies are fighting to hang onto their cookies, although not strictly out of sensitivity to Web privacy -- they want the juicy consumer data for themselves. Realising that there can be valuable marketing insight in precisely how many visitors move around their sites and ads, General Motors, Procter & Gamble and Ford Motor are leading a list of companies blocking Internet ad services from spiriting off with their data. Terry Sullivan, a GM spokesman, said "We've never given anything away." The logistics of routing millions of people around the Internet as they click from, say, a Ford ad on one Web page to the car maker's site itself, have largely fallen to a handful of Internet ad specialists, like DoubleClick, Real Media and MatchLogic. To relieve marketers of the aggravation of inserting ads on thousands of sites all over the Web, DoubleClick and the other ad networks store ads from all of their advertisers on central computers. Thus, DoubleClick, and not the actual advertiser, physically places the ad inside all of those pages. DoubleClick and others rely heavily on cookies, the tiny data files automatically created on your computer's hard drive when you visit a Web site, usually for the first time. The file typically contains a unique tracking number, which can be read by the site and ad servers on all subsequent visits. The sites and ad servers can use this data to track you from one visit to the next, tailoring information and ads according to what you've previously clicked on. That's telling data for marketers, and the ad networks collect the data on behalf of the advertiser. Appreciating the value of that kind of consumer research -- and wanting to keep it out of the hands of rivals -- Procter contractually bans its ad firm, MatchLogic, from using any data from P&G Web sites. And it gathers quite a bit. P&G's Web site "Pampers Parenting Institute", for instance, obtains addresses and children's ages by getting online visitors to sign up voluntarily for a newsletter, Parent Page. In return, they are emailed health tips and other information tailored to the baby's age, and mailed coupons for P&G baby products. On return visits to the site, consumers are urged to update their profile, including the ages of additional children. The site also enables visitors to email the page to a friend. On the site for its new haircare brand, Physique, P&G asks the visitor for a ZIP code (postcode), and then directs consumers to a neighborhood store with Physique products. By aggregating that data, online experts say, P&G could analyse Physique's popularity in different parts of the country. Even without collecting identifiable personal data, P&G can gauge what does and doesn't work on its sites by tracking viewers' cookies. With them, P&G can tell which topics are most interesting to users, and then change a site to tailor it to a specific consumer's interests. P&G says it believes consumers will soon be able to "fully control their own data". Other companies have moved to protect their online research. IBM bars Web sites where it advertises -- more than 800 of them -- from collecting its ad campaign data. Even traditional ad agencies are starting to see a gold mine of data down the road. WPP Group's J Walter Thompson, whose clients include Merrill Lynch and De Beers Consolidated Mines, recently struck a deal to use DoubleClick as its exclusive ad network in return for receiving the data from its ad campaigns. Web sites are also angling to amass huge user databases, using companies like Real Media to keep out services like MatchLogic's, and let them keep user data for their own marketing purposes. General Motors' approach to blocking its ad firm was rather high-tech. The company engineered a sort of super cookie in order to control the one used by MatchLogic, a subsidiary of Excite@Home. Both cookies get slipped into the computers of Internet users. But General Motors' cookie keeps its data segregated from the big data pools MatchLogic creates to develop profiles of Internet users. What kinds of intelligence does General Motors gather? Visitors to its site are urged to create a personal page where they can store information about financing and prices on the Cadillac coupe they just researched. To sign up, a visitor is asked to type in his or her name and email address. With that information, the company can then send special offers about the coupe they've been coveting. Ford is gathering valuable data by setting up sites for potential car buyers where they can design their dream car. Ford encourages visitors to enter its "buyer garage", where they can "park" their virtual vehicle while they contact a dealer for a quote, secure financing or "simply decide if you're ready to buy". By signing in, potential customers can store up to 10 vehicles for 30 days, and Ford can communicate with them online about their choices. Ford is another MatchLogic customer that has sought restrictions on the use of its data. "They can't sell it to someone else," said Jan Klug, a Ford marketing communications manager. What do you think? Tell the Mailroom and read what others have to say.