Another thing I think is missing is that there should be a terms and conditions link added to the footer if is defined. This would probably the easiest to implement myself in the theme if someone can point out what object holds the information.
The footer is located within the template/decorator/default/template.ftl
Curtis mentioned the template you'll want to edit to add a link to the terms and condition. The template that you can customize to add a requirement that they click a button when registering is /template/global/create-profile.ftl You could probably do this all via themes by editing that template and by adding a client side validation routine that only enables the 'create profile' when the 'agree to terms and condition' checkbox has been checked.
<span class="jive-thread-reply-body-container">/template/global/create-profile.ftl (from what I can tell) is only used when a new user is signing up, and already displays the terms and conditions if they have been setup in the registration settings in the admin menu. In the case I've been asked to look into, the users will have already been created (imported from another system) so they won't go through that create-profile screen.
At this stage it looks like the best I can do is a link in the page footer, and possibly some extra text in the welcome email sent out when the users are created.