1. Natural Social sharing and viral contents
2. Low bounce rate
These are the latest trend to increase the rankings. These days so many sites allow free tools or free services for their potential customers. And collect facebook likes and email.
They expect to get user attraction and reduce bounce rate through giving something away.
That is how many SEO companies giving away free SEO tools for visitors and they visitors will remain on the site for few sites.
If you guys have any new ideas to increase user experience please share it we can discuss about it.