Whenever we submit forms online (while creating new account or submitting votes), it is a customary practice to try to subscribe us to a mailing-list. This is usually achieved with small check boxes ahead of the submit button.
To bring in more people these check boxes are checked by default. Only people who pay attention to the form uncheck them. Over a period of time, people don't pay attention to what is written in the form and uncheck these check boxes before clicking the submit button.
Manchester United (or whoever created their online forms) has paid enough attention to increase in such customers and has redesigned their forms.
Above image is cropped from one of their forms to enlist oneself in the lucky draw to win Ryan Giggs signed T-shirt. It reads "Don't send me details of products, services, offers & events from". So people who are going to uncheck the check boxes as a practice will eventually get subscribed to their mailing list.
This is such a small change but I believe it would have definitely brought them more people on the list.
Note: If anyone of the readers has tried this or planning to try this, I am eager to know the impact.