Rand's post on low referral traffic from Digg inspired me to write about a little-known potential traffic goldmine—Digg comments.  I noticed some time ago that first post comments on front page stories can drive some remarkable traffic.  Here are two recent examples.

Last week I posted the first comment on "4 Gas Saving Myths" just before it hit the main page and linked to two relevant articles about fuel efficiency and gas prices.  This comment generated 1,438 visitors. The first comment on "Is Mythbusters The Best Science Show on the Telly?" about Mythbuster's flawed statistics drove 1,901 visitors.  Thousands of visitors for simple comments? Here’s my guide to traffic from Digg comments.  Read carefully—go about Digg comments the wrong way and you just might get death threats—I’m not kidding, more about that later.     

1. First, your links must post to quality content.  The three articles I linked to above are well-written, well-researched articles.  Two of the three articles that I linked to have even been featured on Slashdot (1, 2).  Quality, of course, is a relative term.  Given the typical Digg banter, the threshold for adding quality content can sometimes quite low. The links, however, cannot point to pages that are clearly blogspam or you are sure to face Digg's wrath.
2. Must be on topic.  This is probably more important than the quality of the link.  It may seem obvious, but if your comment/link doesn’t relate to the article, especially if it contains a link, then it will be buried. 
3. First posts comments are going to receive exponentially more traffic than later posts.  They can set the tone for the rest of the discussion and can be almost as important as the actual article being linked to.  If the Digg article already has a comment then it is usually better to reply to the first comment than submit a new comment.  This is true even if your comment isn’t a direct response to the comment you are replying to.  Otherwise, the first comment will eventually get dozens of replies, pushing the second comment way down the page where it will not be seen by most.  For example, I replied to the first comment on a post about Google searches.  The first post was buried with 16 negative votes which effectively gave me the first post.  This comment brought 509 visitors.  In my opinion, this is a flaw with the Digg comment system where you can only reply to root comments.  It provides an incentive for disjointed discussions.  I suspect that Digg will redo their comment system at some point in the near future.
4. If you are looking for traffic from your posts, it does little good to comment on articles that are already on Digg’s front page.  There are two reasons for this.  First, you no longer have the first post advantage and your comment will be lost among the masses.  The second reason is that the highest amount of traffic will come while the post is at the top of main page.  Each minute that passes is lost traffic.  It’s much better to find future front page stories from the upcoming stories section.  This is not hard. Checking the “hot in technology” on the right side of the page will show you which posts are most likely to hit the front page in the next few hours. Of course, you can drill down to other topics besides technology as well.  The cloud view and other tools can also be used to predict which stories are most likely to hit the front page.   
5. As with all forums and websites, if you focus solely on promoting your website it will eventually come back to haunt you. All your links and submitted stories should not be to your own sites. 
6. Digg, as a general rule, has a negative bias towards all things SEO and marketing.  If you have a name like SEOmoz (sorry), there are some people that aren’t going to give you a fair shake. 
7. Digg does not use the NoFollow tag.  However, if you receive a 'thumbs down' from four users your comment will be hidden by default.  At some point in the future Digg may follow Wikipedia's lead and move to NoFollow tags.  I'd recommend it to prevent link spam but generally the community is quick to bury.
8. Realize that although you may receive many new visitors they may be less likely to stay around than traffic you receive from other sources.  As you can see from the statistics below, the bounce rate was between 74-92%.  The average time on site was 20 seconds for the Mythbusters article and just over a minute for the fuel and gas articles.  I'm sure that there are ways the site can improve its stickiness (any ideas?), but the point remains the same—Digg visitors are less likely to stick around than traffic from other sources.
   
   

By way of full disclosure, the site I linked to, OmniNerd, is not my site.  I have no financial relationship with the site and don’t know how their GoogleAds performed, but I suspect that very few visitors from Digg clicked on ads.  If AdSense earnings are your primary motivation, Digg is probably not your best option.

Although this is not my site, OmniNerd did let me peek into their Google Analytics for this story.  Since the stats used above are from Google Analytics and not the server logs, the actual traffic may be higher than I reported. According to something I read on StumbleUpon, “A large portion of...Firefox users have added the NoScript add-on to their browser. This is one of the top-10 most popular extensions for Firefox. This extension blocks any javascript calls...caus[ing]...Google Analytics...to not work."  If that's true, then the actual traffic from these comments could be higher than recorded.  Currently  about 50% of OmniNerd's recorded visitors use Firefox. How many are not being counted?  Does anyone have experience with Google Analytics not counting all their traffic?  

Although Digg comments can be a valuable source of traffic, the reaction to spam can be painful.  A couple months ago Chandler Kent learned that the hard way when he submitted a comment with a link to his blog under his name, as is common practice in most forums.  It quickly received hundreds of “thumbs down” but didn’t stop there.  Someone posted his phone number and he began to receive creepy phone calls and comments such as he "deserves to be  hunted down and stalked."  Ironically, his recounting of the fallout was widely publicized as “The Most Hated Comment on Digg” and brought him a ton of traffic.