It would be nice if you could control a free-text box above the form on the 'become a member' page, so you could explain why the person should fill out the form. People are just as likely to enter a site and land right on the sign-up page (via a Google search, for instance) as they are to get there via a home page. With the latter scenario, they probably know what the form is for. With the former, they'll have no idea why they should fill the form out. And really, for either instance, you should be able to explain the benefits so you can drive the customer to take action.
And... 'organization' shouldn't be required on that form. Firstname/lastname/email is adequate....