Capture email before customer creates Members Area account

Is there a way to capture a customer's email before they create a Members Area account?  Right now, the Members Area sign-up block requires them to create an account with their name and password.  I am creating an ad landing page and simply want to capture their email, and THEN prompt them to create an account.

Would also love an answer to this - having serious problems with new members signing up but not being captured for email marketing.