There are some WordPress sites where you may not want to include the URL field in the comment form. It’s not always necessary and spammers tend to use it to link to their spammy websites, which will be posted in your comments if you have auto approval turned on. Just to be safe, you may want to remove that URL field altogether.
Block WordPress Spam Bots: No CAPTCHAs, No Questions, No Math
Spam is one of the most irritating aspects of managing a WordPress website. Tired of dealing with CAPTCHAs and stupid questions on your comment forms? Check out BotBlocker, a new plugin with a unique method of killing comment spam.
How does it work?
BotBlocker utilizes honeypot technology. Essentially, it tricks the spam-bot into identifying itself by performing actions that a human could not.
The best thing about this plugin is that it doesn’t inconvenience your visitors. It’s also very easy for you to use, since it works out of the box and there are no API keys required.
BotBlocker features:
Automatically stops spam-bots from commenting

Add a Rich Text Editor to WordPress Comments
Not every visitor to your WordPress site will be comfortable using markup. You can make it easier for people commenting by adding a rich text editor to the WordPress comment form. Rich Text Editor for Comments is a new plugin that does this for you.

How to Quickly and Easily Customize the WordPress Comments Form
Many WordPress themes utilize the standard WordPress comments form. Introduced in WordPress 3.0, it’s meant to be a simple tag to output a complete commenting form within a theme template. Making minor changes to the form might seem baffling at first, but it’s really not too difficult.
Step 1: Don’t hack the core.
Here’s the most important tip: Don’t edit the /wp-includes/comment-template.php file. Someone may have suggested it to you in the forums as the quickest way to customize the comments template, but it’s never really a good idea to edit the WordPress core files. There’s a better way.

