Web site owners will be able to trade in their cumbersome Internet addresses for more streamlined names with a service unveiled last week by Los Angeles-based IBoost.com. Millions of people who have posted their own Web sites have been stuck with long and confusing addresses such as http://www.geocities.com/TheTropics/Beach/3081. IBoost's Nethop service will allow them to sign up for names such as "Shop.nethop.com" or "Games.nethop.com." Web surfers who type the simple addresses into their browsers will automatically be forwarded to the Nethop customer's site. IBoost plans to offer the service for free and make money by selling ads that appear along the bottom of its customers' sites.