Jick

<a href="http://www.jamesdimick.com/creations/olark-for-wordpress/" rel="nofollow ugc">Now Olark for WordPress!</a>

Hab.la for WordPress

burningpony

Olark for WP makes it easy for WordPress authors to offer live help/chat on their sites. Or even just a one-on-one chat mechanism. Simply drop in the plugin, enter your Olark account ID, and start chatting with your site visitors through your favorite IM client. No complicated settings, one file to drop in, and best of all it’s FREE!
To learn more about Olark and how it works visit (the official Olark website)[http://special.olark.com/cDBMP].
Get more support at <a href="http://burningpony.com/blog/index.php/2011/05/olark-wordpress-better-together/" rel="nofollow ugc">the official Olark for WordPress page</a>.
<h3>Known Issues</h3>
<ul>
<li>FireFox May Have Issues with the Olark Control Panel</li>
</ul>

Olark for WP

Olark for WP makes it easy for WordPress authors to offer live help/chat on their sites. Or even just a one-on-one chat mechanism.

Hab.la for WordPress vs Olark for WP