Strategy to get X many users that have visited any pages that directly link to the current page

Strategy to get X many users that have visited any pages that directly link to the current page

Forums have a "x many users online". And "X views" on each threads. What I want is how many users have visited the pages that link directly to the thread in place of "X views". Sort of combining the two features to give a better information.
What's the best way to achieve this? (I'm familiar with wordpress and drupal)