When folks think of Digg, they're often misled into believing that the content seen on the homepage is representative of what a wide base of Internet users think is news-worthy and important. The numbers tell a different story - that of all stories that make it to the front page of Digg, more than 20% come from a select group of 20 users. Digg isn't shy about hiding this fact, their top users page plainly displays the statistics:

Digg's Top Users Page

These Top 20 have contributed a total of 5257 stories that have reached the frontpage out of a total of 25,260 stories to ever reach that page - 20.81% to be exact. Many of these top users have, as Digg terms it, a popular ratio of 30% and higher, meaning that almost 1 out of every 3 stories they submit will reach the homepage. Several users (specifically DarkHack & OsterMayer) have popular ratios of over 60%.

A logical extension shows that the top 100 Digg Users have contributed 14,249 stories to the homepage, or 56.41%. At Digg, a very select group of users is dominating the popular homepage content. Far from being a mass of opinion, Digg is instead showing, primarily, the content opinions of just a few, select folks.

There's certainly nothing wrong with this - it's not a secret or a problem and it isn't hurting Digg's popularity, reputation or importance. But, it is something that many folks who use the site don't realize and many marketers or folks attempting to use it to promote their content should be aware of. Like the college frathouse, it pays to know the right people at Digg.

UPDATE: A few good addendums from the comments and some folks in our office  that should be included:

• Cameron Olthius points out that Digg's front-page algo favors submissions from historically successful users and that those users frequently have large bases of friend groups, helping to make their submissions more visible from the start
• Digg's populist power could be compared well to the del.icio.us/popular list, where a huge number of submitters contribute the content (though it's harder to tell unless you're looking at scraped results over time).
• It was noted that heavy users of Reddit & others typically contribute in a very similar way, so Digg is by no means an outlier in this fashion.