Comment is king
The first time I implemented a commenting system for a website was way back in 2003, the same year that the Wordpress blogging software project started. Blogging technology has come a long way since then, and the ability to comment on blog posts are, in my humble opinion, one of the key factors for the success of blogging as a communications medium.
It allows blog readers to engage in a way that was really never possible before. Commenting has even made it out of the blogosphere proper, with many sites allowing visitors the ability to comment on web pages of all shapes and sizes.
To put it into perspective, that site I mentioned above, DavidMcWilliams.ie (which is now running on Wordpress), has over 8,000 user contributed comments on some 500 content pages. Byte for byte, the readers of the site have generated more content than the original author!
All well and good, but what are the benefits of having comments on your website?
I think first and foremost, allowing visitors to comment gives them a form of ownership of a little part of your site, and engenders a sense of community over time. Now that their own thoughts are part of your page, they will be more likely to revisit that page again to what others make of their comment, respond to replies directed at their comments, and as I have seen on a number of sites, form alliances and sparring partnerships with other vocal readers.
All this translates to repeat visits and more content on your site, some of which may generate even more traffic.
The second benefit, which may or may not be applicable (it very much depends on the subject matter of the original content) is that quite often readers will contribute new facts or suggestions that the author may not have been aware of.
So on the plus side we have more traffic, a more loyal readership and increasing your own knowledge.
On the minus side, you will of course need to keep an eye on who is posting what. In general, this has never been a major issue, though if the topic is a particularly contentious one, you may see tempers flaring. Of particular annoyance is comment spam, but there are are ways to alleviate this.
There is also the possibility that you may be proven completely wrong in your assertions and made to look a fool by a more intelligent reader, but the last time I checked, there is still plenty of room on the Internet for crackpots, nutjobs and people who are just plain lying, so I wouldn’t worry about that too much 
So how has this worked for the case study I mentioned previously?
Well at the moment, the more recent articles on the site are generating an average of 70+ comments. An October article smashed our previous best with 184 comments contributed to it. This however, correlates directly to the subject matter which is generally quite long articles relating to the economy (and this of course has been a hot topic lately).
The site has a core group of approximately 20-30 readers who regularly contribute comments and opinions, some of them of extremely high quality and almost worthy of a blog post of their own!
The length and complexity of the original content will have a direct bearing on the level of debate that is going to take place within the comments. An article pushing for an end to capitalism leaves a bit more room for people to give their 2 cents worth than say, a two line blog post saying your cat has the flu.
In my next post I will be taking a look at some of the many plugins and features available within Wordpress to handle commenting, and which ones I have found particularly useful.