We're often seeing new and inventive ways our customers are using our APIs, and one that got us particularly excited was Svbtle's signup.
As soon as you've entered your email in Svbtle's registration form they make a request to Clearbit's Person API, look up the email, and use the returned information to populate the rest of the form. Go ahead and give it a shot!
This is a pretty neat way of reducing signup friction and quickly filling in some fields that may not be in the browser's autofill history (like bio). It's also a great way of finding a user's avatar without asking them to upload their own image.