The biggest means to increasing regular readership is involving your occasional readers through a better comment experience.  These five pugins will do just that if you do it right.

1) Nofollow Free:  Without going nofollow free few small blogs have a hope in hell of drawing lots of comments straight out of the box.  You will get some spam, but nothing worth having comes without a little bit of work.  there are easy ways around this too.  Akismet will block most spam.  Moderated comments will hold all of them until you can look at them.  You can also moderate them so regular commentators can post without moderation. You can also set it so the nofollow doesn’t kick until you have X number of approved comments.  At the very least the  plugin writes “Comments links could be nofollow free” to the end of the comment form, and this is a popular Google search phrase.

2) CommentLuv: This is one of the best ways you can reward your visitors.  CommentLuv will give a title and link to the latest blog post of the commentator.  This deep link will help them in the Google rankings.  It also makes you a popular destination spot.  Once again you can get some comment spam, but that is trivial as having a link directly to their website paints them as an asshole should you choose to publish it.  The same rules for moderation apply with CommentLuv.  This plugin also adds “Enable CommentLuv which will try and parse your last blog post” which is another popular Google search phrase.

3) Brian’s Threaded Comments: This plugin requires a little bit of work.  You have to replace your themes comments.php with the provided comments.php before activating the plugin.  This is a simple matter and you will likely want to edit the plugin itself through the WordPress Plugin Editor.  I find the default border color and width too light to really stand out and show the threads, but it is an easy fix.  This plugin also moves the trackbacks and pings to the bottom of the post rather than intermingling them with actual comments.

4) Quoter:  With Quoter you and your readers have the ability to both quote article text, but other comments.  If you run a hotly contested blog like politics or other charged subjects you almost certainly will want to use this with some sort of comment moderation.  It is powerful, and like the others has the power to be misused.  This is just one more instance where you need to actually work your blog rather than thinking you can sit back and do nothing.  Quoter is another plugin that will require you to add a bit of code to the comments.php.

5) Subscribe To Comments: This plugin makes it easy for people to track new comments by email of posts they care enough to comment on.  “Subscribe to comments via email” is another Google search phrase popular with people looking for blogs to post on.

All in all you have to ask yourself do you want people who are searching for places to comment?  My answer is most definitely.  There will be some assholes who leave spam, but most people are going to read the article and post something relevant to avoid linking their name and blog with spam activity.  Not everyone who searches for these terms will comment on your blog if it isn’t interesting so you must have good content.  in the end you really have to decide what level of commitment you your blog and its readers you want to have.  If the answer is very little you probably should just quit blogging.