My use case is that I have an event with limited capacity but we expect it to be oversubscribed and that we will repeat it. The waitlist feature allows me to collect extra participants very nicely. But there will also be people who are interested but can't make the specific date and I would like to capture these. I know I can have a separate form for them to register their interest and collect them in a group, but I'd prefer to collect them as participants. Ideally, I'd do that with a different participant status ("Interested") but I don't think there is a way to do that. A second event would be fine, but I can't give it a date at this stage.
I'm using WordPress so the fancy form features of Drupal are not available.
Notes on petednz's answer: I used a radio option in the price field for registration or just interest, but it counted both options towards the event participant count even though I set the interest option not to count. Also when the waitlist is activated then the price set doesn't show so I can't distinguish between wanting to be on the waitlist and interest in future events That means I can't use the waitlist for two reasons, but I can live with that and deal with the waitlist that from my interest list manually. But when I set the registration option to my maximum number of attendees, I got this error when I tried to book for another so wasn't allowed to continue registering interest. Is this a bug? Using CiviCRM version 5.35.1 on WordPress.
Fatal error: Uncaught Error: Call to a member function freeze() on string in /home/customer/www/staging10.crm.coma.org/public_html/wp-content/plugins/civicrm/civicrm/CRM/Price/BAO/PriceField.php:209 Stack trace: #0 /home/customer/www/staging10.crm.coma.org/public_html/wp-content/plugins/civicrm/civicrm/CRM/Price/BAO/PriceField.php(439): CRM_Price_BAO_PriceField::freezeIfEnabled('<span class="cr...', Array) #1 /home/customer/www/staging10.crm.coma.org/public_html/wp-content/plugins/civicrm/civicrm/CRM/Event/Form/Registration/Register.php(627): CRM_Price_BAO_PriceField::addQuickFormElement(Object(CRM_Event_Form_Registration_Register), 'price_48', '48', false, '0', 'Choice', Array, Array) #2 /home/customer/www/staging10.crm.coma.org/public_html/wp-content/plugins/civicrm/civicrm/CRM/Event/Form/Registration/Register.php(400): CRM_Event_Form_Registration_Register::buildAmount(Object(CRM_Event_Form_Registration_Register)) #3 /home/customer/www/staging10.crm.coma.org/public_html/wp-content/plugins/civicrm/civicrm/CRM/Core/Form.p in /home/customer/www/staging10.crm.coma.org/public_html/wp-content/plugins/civicrm/civicrm/CRM/Price/BAO/PriceField.php on line 209