Voodoo chat  

Voc is a stream-chat engine which is designed to work on high-loaded chat-servers. It is written in PHP, but uses Perl or C++ for Voc-daemon -- the special program to handle multiple user-connections. With Voc you can establish a chat which will serve hundreds of visitors simultaneously. And it's html-based, so your chatters can use it from almost any browser. The Voc now has 3 engines, based on: Files, MySQL, SystemV SharedMemory.

Hosting Requirements: Unix, Windows NT/2000/XP
Database: (MySQL)
Price: Free

   chatterbox  

The chatterbox is an fast, advanced and free 'tagboard' or 'shoutbox' system.

Price: Free

   StringyChat  

PHP/MySQL chat/ shoutbox script which can be easily integrated into any PHP enabled website. Optional email notifications on new posts. IP Bans, reserved/ banned words and usernames. Admins can delete/ modify posts, specify presentation via CSS, and control output.

Hosting Requirements: PHP
Database: MySQL
Price: Free (GPL)

   Ji-takz  

Free tag board for everyday use. Still in development. Features: tag (multi) reply - customizable message string event handler - customizable display css.

Price: Free (GPL)

   NoiseBox  

NoiseBox is a powerful shoutbox / tagboard script that allows visitors to chat on your website and leave messages. It is fully featured, and includes: User-friendly administration control panel - Flatfile storage - Emoticons - IP and IP mask blocking - Username registration - Fully customisable design - Anti-flooding control - Automatic link parsing and more.

Hosting Requirements: Unix, Windows; PHP 4.1+
Price: Free

   LimiBot  

A PHP/mySQL driven IRC bot. Full admin system, including a live web interface and IRC admin access aswell. Advanced statistics system. Dynamic loading system to load addons on the fly without need for a restart, making bot uptimes high and stable.

Hosting Requirements: Unix, Windows
Price: Free (GPL)

   Dawg Tag  

Dawg Tag is a tag board script with a full admin section. The admin user can set all appearance options, block IPs, and delete posts. There is also an email notification option to let you know when someone tags you.

Hosting Requirements: Unix
Price: Free (GPL)

   FlashChat  

FlashChat is a simple, customizable chat room that anyone can add to their website. It includes support for multiple chat forums, administrative controls, and over a dozen IRC-like options. The current version of FlashChat allows extensive customization of the chat themes and background, and which interface elements to show or hide. It also integrates easily with your current user database. Administrative controls exist to change the frequency of chat refreshes to reduce the load on your server, and also to set the maximum message size to reduce bandwidth.

Hosting Requirements: PHP 4.1.2+
Database: MySQL 3.23+
Price: $5

   Website Instant Messenger  

Instant Messenger Features: Simple site integration - Works will all browsers 4.0 and higher - All ASP & HTML or PHP & HTML coding, no ActiveX or Java - Supports simutaneous converstions in multiple windows - cstomizable logo and page titles - Optional bad word filter - User formatting of comments (bold, underline, italic) - Emoticons.

Hosting Requirements: PHP, ASP
Database: MySQL, MS SQL
Price: $499.95

   123 Flash Chat Server  

123 Flash Chat server software is full-featured& high-performance Java chat server plus stunning Flash chat client! It's a fast, easy and affordable way to host and manage real-time communication. 123 Flash Chat server software can integrate existing database of forum or website. It's most-customizable to admin and end-user.

Hosting Requirements: Linux; PHP 4.1+
Database: MySQL
Price: Free