lemonthirst on "displaying the number of active visitors on a single post"

Hi, i've searched/tested most of the plugins available in the repository for a plugin that can count how many users are online on a single post.

I want to display the number of active users reading that post(just that url not the whole site)
Ex. Hello World (2 active visitors)
Hello World 2 (5 active visitors)
and so on based on the number of visitors

Is there a plugin like this?