1.Cbox - "Cbox is a unique commenting and chat widget that combines the best features of regular chat and tagging systems into one ideal solution. And the best part – Cbox Basic is completely free. "
2.Meebo me - "Instant messaging right from your web page."
3.Google Talk badge- "A Google Talk chatback badge will let visitors to your web page chat with you."
4.Shoutmix - "Shoutbox a.k.a tagboard/chatbox, is an easy to use messaging system that allows you to interact with others instantly."
5.Freeshoutbox - "Here you can get a free shoutbox that you can use either as a shoutbox on your homepage, a guestbook or even as a chatroom."
6.Friend Connect - "Google Friend Connect means more people engaging more deeply with your website -- and with each other."
7.Facebook Connect - "Facebook Connect is the next evolution of Facebook Platform -- enabling you to integrate the power of Facebook Platform into your own site."
8.Myspace Shoutbox - Flash shoutbox for Myspace users.
9.Oggix - "Our shoutbox support shoutbox avatar™, reply on entries, unlimited entries and more, all for free."
10.Tag-Board.org - "Tag-Board.Org is a remotely hosted tag-board (aka tagbox/shoutbox/cbox) service.
They are fast, fun, easy to use and packed with lots of great features!"
11.Yahoo status - "Yahoo Messenger Status ID Offline and Offline Notification can be added in the Blog such as Blogger aka Blogspot, Wordpress, Blogsome, and others Blog Platform"
12.Skype tools - Skype blog/website widgets.
13.Windows Live messenger widget Read the instruction s carefully.
14.Userplane - "Userplane™ is the world’s premier social software provider for online communities. "
15.DISQUS - "Disqus is a powerful comment system that easily enhances the discussion on websites."
16.Intense Debates - "IntenseDebate's comment system enhances and encourages conversation on your blog or website."
17.JS-Kit tools - Quite advanced services , a must see.
18.Twitter - "Twitter is a free social messaging utility for staying connected in real-time."
Feel free to suggest cool chat / comment tools not in the list.