Did you know you can use URL query parameters to populate HubSpot form fields? Handy for scenarios such as passing data collected on one page to a form on another page e.g. if a visitor is sent from a product/service page, then populate that product/service into your form on the next page: Auto-populate form fields with a query string
Also on the topic of URL parameters, did you know you can use HUBL to dynamically change the text on your HubSpot pages based on URL parameters? Useful for creating paid landing pages where keywords change based on the parameters sent through the ad URL.