That their credit information is probably safer than when entrusting their card to a waiter or gas station attendant. Give people a reason to buy from you. If you can't compete on at least some of these points you won't do much business on or off the Internet. The other side of the economic motivation is people's attraction to free products. A good part of the shareware industry is based on giving away fully or partially functioning products with hopes of enticing the user to register or pay for an upgraded product.
Information is sometimes the hook.
PC Magazine's early strategy was to offer an article or two per issue as a way of getting you to come to their Web site, and then show the complete table of contents of the current issue with an opportunity to subscribe to the magazine itself. Contests are another form of the same motivation, though you still have to advertise the contest heavily to get people to come to your Web site to participate. A fourth motivation that draws people to the Internet is social, human interaction, closely related to the entertainment motivation. Chat rooms, news groups, and mailing lists proliferate on the Internet. The Web form of these is an interactive Web page where one can read others' messages and leave one's own on a number of topics.