Observers say America Online's purchase Monday of online organiser When.com is likely to mean that all of the major Internet hubs will rush to get in on the game -- all the sites, that is, that don't already have organisers of their own. "The portals are in a foundation period; the companies want to get all the services and applications they can, to be competitive with the other portal sites," said analyst Bridget Leach of Giga Information Group. "They'll keep doing that until, who knows ... there's no stopping point that I can see, really." The pattern has become familiar: one of the top handful of Web sites adds a new gadget or tool that encourages users to stick around, and the others follow suit with something similar or identical. Repeated over and over again, this Cold War scenario has led to super-sites such as Yahoo!, Excite, Walt Disney Co.'s Go Network, Microsoft's MSN.com and Lycos Inc. being almost identically loaded with everything from maps to message boards. But there's one difference with online organisers: the "content" of the service is created by the user, in the form of reminders, address books and even interest groups -- it isn't available on any other site. "I call that 'precision munitions' for portals," said analyst Jae Kim of Paul Kagan Associates, a media research firm. "Branded, mass-media content is a carpet-bomb approach -- flood them with information and hope some of it sticks. But when you roll out services created by users, it's highly relevant to them and nobody else, and the likelihood is far greater they will come back and generate page views." When.com is just one of over a dozen organiser services that have launched in the past few months, each offering a different set of options. When.com's focus is on providing a large amount of schedule information -- from live events to trade shows -- that can automatically appear on a user's personalised calendar. Other options include creating a personal work-group for scheduling group events and setting reminders for birthdays or anniversaries. Several Internet hubs already have organisers built in. Lycos offers MyTime, while Yahoo! has Yahoo! Calendar. Amazon.com, while in a different line of business, offers a service that reminds users when a gift-buying date is approaching. Online organisers also seem to be a successful example of a business the portal sites desperately want to get into: Web-based applications. "This is a good example of what an Internet-based application should look like," said When.com CEO and co-founder Ted Barnett. "It has dynamic content and group activities, and scaling is important. Every application you can think of will ultimately have some Web component to it." The online component means that your calendar can be automatically updated as new events are scheduled, and it allows collaborative scheduling -- two features that would be impossible for desktop-bound schedulers such as Microsoft's Outlook. While online organisers already work reasonably well, experts caution that the technology for such Web applications is still at an early stage. "The problem with some of them is that people aren't getting the same type of service that they would get from a desktop application," said analyst Leach. "The user interface is not as nice, and there are more advanced features on desktop calendars."