Hi: A company can use the internet to gain a competitive advantage in marketing in several ways. Many companies are involved in social networking. Several designers have hired folks to tweet for their company. Here is a link to an article that explains more: http://online.wsj.com/article/SB10001424052748704285104575491761543648510.html
In addition, some companies use Foursquare and Facebook to have people check in and have flash sales/events. Here is a link about this: http://gigaom.com/2010/08/16/foursquare-future/
Another link ...
This detailed solution gives multiple suggestions for using the internet to gain a competitive advantage in marketing.