1. Akismet
Akismet checks your comments against the Akismet web service to see if they look like spam or not and lets you review the spam it catches under your blog’s “Comments” admin screen.
Want to show off how much spam Akismet has caught for you? Just put akismet_counter code in your template.
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2. Per Post Comment Text
A plugin that allows you to set the text of your comments link on a post per post basis.
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3. Subscribe to Comments
Subscribe to Comments is a robust plugin that enables commenters to sign up for e-mail notification of subsequent entries. The plugin includes a full-featured subscription manager that your commenters can use to unsubscribe to certain posts, block all notifications, or even change their notification e-mail address!
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4. Comment Recovery
Ever lost your comments by fooling around with your Database? So did I. Now this is a comments recovery plugin. Just paste the E-mail sources of your new comment notification emails and save.
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5. Highlight Author Comments
Highlight Author Comments automatically displays comments made by a post’s author in a distinctive style with no need to edit your template files, etc. All you do is provide a snippet or two of CSS styling to be applied to author posts.
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6. Maximum Number of Comments
This plugin enables the setting of a maximum number of comments allowed to display in each post. In addition, it provides a link to expand the comments showing all the remaining ones.
All the comments above the defined maximum number are hidden. By clicking on the link ‘Click here to see the remaining comments’ they will be shown.
On the Plugin homepage you will find these description and instructions:
in English
in Portuguese
Author: zelopes
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7. AJAX Comments
More than that, it checks if all fields filled correctly, and also makes sure to avoid comment duplication, and has flood protection capabilities as well.
Probably one of the best ways you could spice up your WordPress Blog with AJAX; readers love it! Must see for yourself.
This plugin works well in all major Web browsers, and uses discrete AJAX. That means if JavaScript disabled, it’s using the original comment posting method.
Ajax Comments known to work well, with Authimage plugin, but I rather suggest Akismet, as it is free for personal use.
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8. Ozh’ Absolute Comments
Absolute Comments is a comment manager plugin that lets you instantly reply to comments, either from the original Manage Comments administration page, or from the email notification, without the hassle of visiting the post first.
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9. WordPress Thread Comment
This Plugin is an enhancement for WordPress’s comment function. It enables users to reply on a exist comment, and the discussion will be displayed threaded or nested.
Features
One can reply on any exist comments.
The discussion will be displayed nested or threaded.
Easy to install. No hacking on WordPress or your theme is needed.
W3C compatible.
Customizable HTML / PHP / CSS on admin section.
AJAX support, enables to comment without reloading the whole page.
Choose AJAX or not freely
Get notification by email when reply is available.
Can manage comment in front-end(move comment, delete comment)
Requirement to themes
If you wish to use AJAX, the comment objects of your theme must has an ID like “comment-xxx”. It’s a standard of WordPress themes now, yet some themes may still not meet this requirement.
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10. Suggest Comments
This plugin is just for fun. Sometimes a visitor would like to say that he likes a post. Suggest him some standard phrases.
It’s still in developement. So check for new releases daily!
New features in 0.8 Enable/disable for posts and pages seperately Randomize comment list
Fixed in 0.7 quotes can be used now implemented support for “comment” and “comment-text” textarea id’s activation might have caused problems with WP version < 2.3
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