Many blogs offer the option to leave a comment. There are multiple ways to leave them. The blog could utilize a Facebook plug-in that allows someone logged into Facebook to comment easily. Other sites use blog membership plug-ins with similar functionality, like Disqus. However, many people find these can be troublesome down the road when the company changes its terms, starts charging money or goes out of business.
The best solution is to offer an open comment form that allows the person to submit their name, email, comment and website. The website option is for those people commenting on behalf of a company or their own blog.
Often times we get asked by businesses “Should we approve comments from competitors or other businesses?”. The answer to this is yes and no. If the comment is an obvious generic comment meant just to link to a site or blog, do not approve it. If the comment is a real comment with good feedback, sure, approve it. After all, that’s why the website option is in the form in the first place. Linking to useful or relevant sites is good for SEO ranking.
You are going to want to link to your site from other folk’s blog as well. There is no harm to having healthy inbound and outbound links and many SEO studies have shown it is beneficial.
Google wants the internet to be a social place where people can get good information without trickery or clutter. Many sites on the web just close their comments section because they don’t feel like they have the time to sort through comments and approve or reject them. That is a big mistake. Giving people the ability to give their input on a blog increases the chances that they will return. Also, building a strong blog with plenty of content but not taking the time to interact with the readers is definitely counterproductive. You can fend off robot or spam comments by installing one of the many spam filters available. Currently, askimet is the most popular spam comment blocker for WordPress.
Lead Developer at Olympus Web. I started this company in 2002. I specialize in Search Engine Optimization and building websites for small businesses.