(FORTUNE Magazine) – Going online provides investors with the opportunity to rub elbows with one another in cyberspace and come away with lots of information, including many a stock tip. Take Greg Markus, 45, a political science professor at the University of Michigan in Ann Arbor. Nine months ago Markus started subscribing to America Online to help himself stay on top of the technology stocks he holds, such as Intel. While surfing the system, he encountered a discussion of whether Cisco Systems, a supplier of data communications ! equipment whose share price had recently fallen by some 50%, was a good bet. Says Markus: "The drift of the discussion was that the company was sound and the drop unwarranted. I bought in in the upper teens and again in the low $20s." When the price hit $30, he sold and took a $5,000 profit. The stock recently traded at $33.50. CompuServe and Prodigy, the other two main online services, offer similar investors' message boards where subscribers ask questions and trade tips, often amid raging disagreement. The boards are organized by such topic areas as equities, bonds, annuities, and mutual funds. You can visit one of these areas to call up all recent messages relating to a particular company, say. Then you can simply read the messages -- "lurking," it's called -- or you can weigh in yourself with a question or opinion. Very likely, your fellow subscribers will come right back to you in real time, or what they have to say will be waiting for you next time you log on. Because messages automatically include the name -- or in some cases handle -- and online address of the sender, you know whom you're dealing with and can respond in turn, privately if you like. On an average day the investors' message boards for the three main online services get as many as 1,000 new postings apiece. The subsequent back and forth turns them into computer-age chain letters. Not surprisingly, the most provocative subjects tend to garner the most responses. For example, "Gold Ready to Rumble," a bullish message posted on Prodigy on October 25, had 66 replies by November 15. So far, gold prices have declined to move much.

THE WORD on the street is that CompuServe offers the most serious forum, thanks in part to its history of providing investors stock quotations and other market data. America Online wins plaudits for being an easy system to navigate. Prodigy gets slammed for outdated graphics. Even so, all three offer comments from a wide range of investors. Says Jack Rickard, editor of Boardwatch Magazine, a Littleton, Colorado, monthly devoted to assessing online services: "If you see a tip, it may be from one of the top brokers in the country or it could be from an 11-year-old kid." Overall, the message boards are replete with investors who have shown themselves to be knowledgeable, often to the point of developing a following. What these "virtual experts" post, other people on the system heed. Want sound information on mutual funds, for instance? Turn to Barbara Golds, 58, who | contributes to America Online from suburban Detroit. Last year she took over the profit-sharing plan at her podiatrist husband's practice, confident she could beat the 7% net return produced by the firm's professional money managers. She's up 10% so far in a tough year. Her picks include Janus Mercury and Warburg Pincus Fixed Income. Search hard enough and you can find someone out there on top of almost any investment subject, even the most obscure. Lou Truex, 40, a math teacher and wrestling coach in Lawton, Oklahoma, is part of a Prodigy group that digs up and posts hard-to-find information on non-U.S. stocks. These include Cifra, a Mexican retailer. He paid 91 cents an ADR in 1991. Current price: about $2.70. Says Truex of his unusual extracurricular pursuit: "It's a lot of fun. And sometimes you beat the big boys, so it can pay off too."