Number of users online / Who is online
I have added a prototype plugin that uses Pusher.com to keep track of online users.

Check out the Git repo.

Basically you need to add this to your frontend template:

{{ craft.whosaround.setup }}


It adds the Pusher library, and also subscribes to the channel name you got in your settings. You need to signup to an account over at Pusher.com as well.

In the CP, you can get a rudimentary list with the name and the count.

I can think of some cool use cases, so I'll probably revisit it soon and add more stuff etc., but it might be a useful starting point, depending on if you want to use Pusher for this.

Pusher is a very neat service for use cases like this, and might be especially interesting if you expect many users online.