Each offers the basic ability to send instant messages, but most also have unique features appealing to their users' interests. And at the moment, users of each service can only interact with others on that service.
ICQ (the Oahu of the business, so to speak) sets itself as firmly focused on its member community, and has developed a network of "user-created content," including chat rooms, message boards and member directories.
"The best way of saying it is, it's a communications portal," said ICQ COO Fred Singer. "You can send a message to somebody, or a file, a URL, a voice message, a greeting card, or an invitation into a chat." A newer set of features helps users search for other members with similar interests. Many of the advanced features made their debut with the software's latest release, ICQ 99a.
ICQ also aims to be a kind of all-purpose desktop control panel, connecting users directly to Web searches and personal organization tools.
Yahoo! Inc. (Nasdaq:YHOO) has gone in a more business-like direction, trying to appeal to the type of person who checks his stock portfolio from an Internet kiosk moments before boarding a plane. Yahoo! Pager can notify you of a change in the price of your favorite stock, by either virtual or real-world pager, and the company plans to add news alerts and sports scores.
Pager also has a calendaring feature, through which it can remind you of appointments or birthdays.
If all this reminds you of another once-hot technology -- Push -- you're not alone.
"People I talk to bring that up a lot, 'Pager is going to become Push,' " said Yahoo! Pager producer Brian Park. "But it's push that people really want. It's related to specific preferences you set -- you want to watch certain stocks, or you have a meeting at a certain time."
AOL's instant monster
America Online's (NYSE:AOL) Instant Messenger has the prime advantage of giving access to AOL's 16 million members, but the company has also added direct links from the AIM client to a personalized news page.
Users can also click over to several search and directory pages.
Down the road, some experts see instant-messaging standards emerging that would bridge the archipelago, but no one sees that happening any time soon.
"If users ask for [a standard], eventually it will happen," said Yahoo!'s Park. "It would have to be a union of all the major products. But if a standard emerged, we'd be happy to adopt it."