The battle for audience and revenue among the Internet's top sites is intensifying this month, with several of the "portals" rushing to add services, redesign their pages and buy up competitors as they chase leaders America Online Inc. and Yahoo Inc.

For Internet users, the competition means--at least for now--continued free access to the slew of features offered by the sites, including financial services, electronic mail, personal home pages, calendars, instant messaging and chat.

Yesterday, Internet holding company CMGI Inc. capped a month-long buying spree by rolling out its remade AltaVista portal--a gateway that combines news, sports, search engine, shopping and other services--and kicking off a $120 million advertising campaign to promote it.

Another major site, Excite At Home, agreed to acquire Blue Mountain Arts Inc., the World Wide Web's most popular site for electronic greeting cards, for $780 million in stock and cash. Also yesterday, Lycos Inc. released a revamped shopping service that adds a loyalty rewards program, a suite of comparison-shopping tools and product reviews from users.

And the sleeping giant in the portal wars, Microsoft Corp., is preparing to unveil a redesigned MSN.com portal that aims to offer users improved access to the collection of specialty Web sites the company has never been able to unify into a coherent network. Even as competitors play catch-up, AOL rolled out its own new shopping and photo service this month and announced yesterday that it has surpassed 19 million subscribers.

"This is all about who owns the customer," said analyst Bill Whyman of Legg Mason Wood Walker Inc. "Because in the consumer Internet space, revenue and earnings flow from strong customer relationships. So all the things we are seeing . . . are ways to keep the customer coming back to your site, staying longer, sharing more data and making the site an integral part of their lives."

Each player going after Yahoo and AOL has a strategic plan with a wrinkle or two it hopes will help make them stand out in the me-too world of Web portals. There are slight differences among their overarching strategies, especially the degree to which they rely on Internet access, advertising and commerce to make their money.

AOL's hallmarks are its huge dial-up telephone access and hyperactive chat rooms. With more than 21 million subscribers paying for access, including 2.2 million for CompuServe, AOL derives more than 60 percent of its revenue from access fees. Its vast audience also allows it to collect bigger advertising and e-commerce revenues from merchants than other portals can charge.

Microsoft (with 2.5 million paying subscribers) and AltaVista (with more than 600,000 free Internet access subscribers) are the only two Web portals that are aggressively marketing dial-up Internet access. Excite At Home, meanwhile, is trying to attract subscribers to its more expensive high-speed cable Internet access.

Yahoo and Walt Disney Co.'s GO Network are not focused on access. Yahoo's strength has been its popular Web directory and integrated suite of services. GO has lagged in traffic and has focused on promoting Disney's own content at such stand-alone Web sites as ESPN Sportszone and ABCNews.com.

AltaVista, the portal that has lagged the most in traffic, is attempting to catch up quickly this fall by giving away free Internet access offered by an Internet service provider that CMGI bought last summer. Also, AltaVista is aiming its content and advertising at veteran Internet users who are not likely to be satisfied with AOL's simplified approach.

CMGI bought AltaVista from Compaq Computer Corp. in July with an eye to making it the central traffic engine for CMGI's fledgling but innovative Web empire. The Andover, Mass.-based holding company bought a string of Web companies this year in a bid to create shared marketing, technology and content resources that it hopes will make the resulting network competitive with AOL and Yahoo.

In the past month alone, CMGI has bought five online technology companies. When those deals are completed, it will own a total of 17 Internet companies, plus minority stakes in three dozen others.

"We believe we have many technologies and services that can help a portal be more relevant and accurate and provide a better cost structure for them," said CMGI Vice President Bill White.

CMGI and Excite At Home have been the most aggressive in letting users customize their Web pages. That's partly because they are also working the hardest to deliver targeted ads based on personal interests inferred from the pages each user visits. Each bought companies that build anonymous customer Web-surfing profiles.

Engage Technologies Inc., owned by CMGI, has created more than 30 million anonymous profiles based on data from more than 400 Web sites. Tapping the profiles, it began marketing a service to Web sites this month that aims to boost ad rates by allowing advertisers to reach a more precisely defined audience--female soccer fans over age 30 who live in Baltimore, for example.

Unlike most Internet companies, the top portals actually make money. AOL and Yahoo are both profitable largely because they collect advertising and commerce revenues and can spread their costs across a global audience. Excite At Home narrowed its loss to 1 cent per share in the most recent quarter. Neither Microsoft nor AltaVista discloses its finances because the portals are subsidiaries of publicly traded companies, but analysts believe both are losing money.

All the portals hope to boost their ad rates and profit margins by delivering ads that are more relevant to the each user's commercial interests.

George Bell, Excite At Home's president, said his company's advertising technology allowed it to collect more money per page than Yahoo did in the most recent quarter, even though Yahoo has many more users. "We do about one-quarter of their page views and three-quarters of their revenues," he said.

CMGI's Growing Internet Empire

Majority-owned operating subsidiaries:

* AltaVista: Search engine and media portal.

* Engage Technologies: Online advertising profiling technology; has created more than 35 million anonymous profiles of Web surfers.

* AdSmart: An advertising network that currently serves ads on more than 300 Web sites totaling more than 2.5 billion monthly impressions.

* MyWay.com: Formerly PlanetDirect, MyWay is a network of local portals.

* 1ClickCharge: Allows people to purchase Web content on pay-per-use basis in small dollar amounts using patented authentication technology.

* ICast: Collects syndicated audio and video content on the Web.

* NaviNet: An Internet access provider.

* NaviSite: Offers Web site hosting and Internet application hosting, monitoring and management.

* Magnitude Network: Internet services for broadcasters.

* SalesLink: Offers services to help with fulfillment and logistics for online merchants, as well as electronic-commerce catalogues, site hosting and online payment technologies.

* ZineZone.com: A collection of Web "zines" that allows users to create their own "zine" based on their personal interests.

* Activerse: Develops technologies for communicating, such as instant messaging and chat.

Acquisitions pending, all announced in past month:

* Flycast Communications--Flycast Network serves 1.4 billion ad impressions per month on 1,200 sites.

* Activate.net--Focused on streaming media for the business-to-business market.

* AdForce--Developer of Internet ad serving and measurement tools.

* AdKnowledge--Provides Web marketing management services.

* 1stUp.com--Internet access provider specializing in free Internet access.

Owns a minority share of these companies:

The company's @Ventures affiliates have ownership interests in Lycos Inc. (Nasdaq: LCOS); Critical Path (Nasdaq: CPTH); Silknet Software (Nasdaq: SILK); Chemdex (Nasdaq: CMDX); Ancestry.com, Asimba, AuctionWatch, Aureate Media, blaxxun, BizBuyer.com, Boatscape.com, buyingedge.com, CarParts.com, CraftShop.com, eCircles.com, EXP.com, FindLaw, Furniture.com, HotLinks, Intelligent/Digital, KOZ.com, Mondera.com, MotherNature.com, NextMonet.com, NextPlanetOver.com, OneCore.com, ONElist, PlanetOutdoors.com, Productopia, Promedix.com, Raging Bull, Softway Systems, Speech Machines, ThingWorld.com, Vicinity, Virtual Ink, Visto and WebCT.