Ask HN: Which user engagement tactics have you tested personally..
At the site that I work the following things made a measurable impact on the traffic, user retention and user engagement:
1) Make content shareable with social networking sites. A year after we implemented this our daily uniques increased by over 70% and social networks generate now almost 50% of the traffic.
2) Create badges for user achievements. After the introduction of badges the amount of user generated content doubled in a month.
3) Create a weekly newsletter to registered users who have not visited the site for a week. This is not as clear cut but after this was introduced the number of daily logins have increased by about 10% (could be a measurement error though).
4) Make the site load faster.
..and which did not make any apparent impact or made surprisingly small one:
1) Running banner campaigns asking visitors to register. Registration numbers didn't budge - maybe our banners sucked.
2) A feature allowing users to follow the content created by other users ala twitter. A few are really using this feature - maybe we had crappy implementation.
3) An invite functionality where users can invite their friends to register at the site. Only 5% of daily registrations come from this feature - I was expecting more.
Just in case you are curious, these experiments were conducted at: spoki.lv