A number of big players in the TV industry are expected to make major announcements within the next several weeks concerning their forays onto the Internet's World Wide Web. Fox this week will reveal its Fox World site, which it is touting as the nation's first truly interactive site with original programming. Later this month, Sony Corp
. will announce the details of a site dedicated to promoting the 21 programs it produces and distributes, like "Seinfeld" and "Mad About You."