Notify user checkbox I'm looking for a bit of code, or module that would insert the following behavior into my user registration flow that exists as a php file.  Use case as follows:


User registers for a free trial
User checks a box that says "Send an email reminder to [WILL AUTOMATICALLY INSERT USER EMAIL].com 3 days before I am charged. 


User checks box. The back-end functionality might need to be manual for now. All I want to do is add the box, text, and have it pull the email address token automatically.
You can add as many field you like to the user object using Fields. Just tell your field to be visible on the main user panel.

Once this is working, implement hook_cron and send your mails using drupal_mail().