View source for Why would the companies be interested in using Second Life?

There are several business opportunities within SL. Users can provide services, sell products and buy products. At the moment there are several big companies that are using second life as means of display their products. There is a market place within the game where you can buy and sell products using a virtual currency call the linden Dollar.
 
According to the SL’s webpage :”Shopping is a big part of the Second Life experience for many Residents. You can buy and sell anything that can be made in-world, from clothes, skins, wigs, jewelry, and custom animations for avatars, to furniture, buildings, weapons, vehicles, games, and more. Once you’re ready to bring your products to the market, it’s simply a matter of buying or sub-renting property, for opening up a shop. There are also Resident-owned malls which charge rental fees, or take a cut of your proceeds. As in the real world, the challenge is to build up a reputation that earns a steady stream of customers.”