Enable social sign in / sign up / login on landing pages and forms
With more and more people using mobile devices to consume content, it's time consuming and fiddly for visitors to your website to fill out a multi-field form on a landing page by typing in text on a small screen.
Some other landing page tools (and standalone third party tools) offer a feature where you can have a "sign up using LinkedIn/Google/Facebook/Twitter" to access content, where it then connects with the person's chosen social account and pulls their name and email address (and any other info you choose) from there.
This takes away the typing in of multiple form fields on a small screen and replaces it with a one click experience for users to access gated content via landing pages.
Here is an example from an article discussing this as an easy way to increase landing page conversions:
This is not new technology (the above article is 3 years old). HubSpot's own blog has an article about this from 2014 as well. It would be great if this were a standard feature in HubSpot landing pages, and would increase conversions on most HubSpot users' landing pages.