wTag is a free shoutbox (chatbox, tagboard or mini chat) script written in PHP, JavaScript + Ajax. You will need a PHP enabled web hosting to add the chat box to your web site.

Shoutbox mini chat script features

wTag is a shoutbox (chatbox or mini chat) that is written in JavaScript and PHP, and using Ajax to exchange data with the server without need to reload an entire page.
It uses MySQL database as backend.
CSS based drop-down smileys menu. You have the option to enable/disable the display of smileys and smileys menu.
Anti-spam filter: blocks messages that contain words or phrases that you set in the configuration file.
Bad-word filter: replaces "bad words" that you set in the configuration file with symbols.
Replace URLs catched in a message with clickable links.
UTF-8 encoding for multilingual support.
Compliance with XHTML 1.0 Transitional and CSS.
Custom designs: it's easy to change the chatbox look by editing the CSS files.
A form validation and warnings display system.