I really shouldn't nitpick-- particularly on something thrown together in a week by one person-- but I can't resist: I bet you'd double the fraction of people

I really shouldn't nitpick-- particularly on something thrown together in a week by one person-- but I can't resist: I bet you'd double the fraction of people looking at the site who actually build a list if it lets you start building a list before signing up. After I've built one you can remind me that I should sign up if I want to keep it. Its much better to let people get their feet wet with out jumping through the hoop of a sign-up.