How do you convince already-registered users to sign up for your latest email newsletter? One way is to offer an incentive. Earlier this week, the Seattle Supersonics offered users the chance to win a $500 shopping spree if they logged into their account and opted-in for the latest email newsletter.

An even more effective method was demonstrated by the New York Times today in the online version of its Business Section. In the upper-right corner, the user's existing email address is shown, along with a sign-up button (see screenshot below). All it takes is a single click to begin receiving the daily DealBook email.

The newspaper also provides a link to view a sample of the newsletter, a proven strategy for increasing response, and links to its Privacy Policy and back to account preferences to change the email address.

Once users click on the sign-up button, the text is changed to a thank-you message along with a link to change email preferences (see inset above).