Buying into the vision that the Web will break down geographical and cultural barriers and create virtual communities on-line, Reebok's Planet Reebok Web site is one of the first attempts to use sports as a unifying theme. Found at http://www.planetreebok.com, the site has an active bulletin board, called "Between Us," and live chats -- with past appearances by Frank Thomas, Roger Clemens and Yankees players transcripted. Yesterday, the site was promoting the company's cross-promotional efforts with MCA/Universal's new movie, "Ed," with "Friends" star Matt LeBlanc. Other key themes are women's sports, with a page devoted to the Women's Sports Foundation and Reebok's Versa Training line both featured prominently. On the Olympics, Reebok and SI are combining to offer journals from Olympic athletes. The Heart & Sole page offers bios of Reebok- backed Olympic track athletes. The Sports & Fitness page offers training tips and a charter on coaching. One interesting feature was a link to MIT's StockMaster service, which tracked the company's stock. Planet Reebok offers plenty of content for sports and fitness enthusiasts. But, as with any Web site, the challenge is to keep the info fresh (THE DAILY).