CF Users Online PHP script is a very simple PHP counter script that allow you to display how many people are viewing your website at any one time. This script will generate a small image (like the small RSS 80*15 button) with then number of visitors viewing your site.The look of the generated image by the PHP script is easy ...

Display Users Online Using PHP is a free and Open Source PHP user management scripts, which is displaying users online using the reference from the last five minutes (300 seconds). You can always change value and display users online according to the last one minute or something.