Q: Who was the pitcher to pitch the only perfect game in the World Series?
A: Don Larsen, October 8, 1956, as the New York Yankees beat the Brooklyn Dodgers, 2-0.
I've seen a few compilations on this subject, but the methodology in some cases seemed either flawed or not objective enough (surprise), so I though it would be useful to conduct my own research piece. If you take the "authority" approach on this, it makes it a lot easier to rank these various sites and eliminate the vast majority since they simply aren't strong enough to appear on the radar.
Basically I got lists of networking sites and did a Google PageRank on all of them. Everything below PageRank 7 was thrown away. That narrowed down the field to 9 sites (boy, that part was easy!). Then, I got the Quantcast.com visitor counts and the Compete.com visitor counts. Then I compiled a composite number of inlinks for each site. Finally, I got the Alexa rank for each.
What I did then was to try and come up with a "fair is fair" composite number that indicated the authority and value of each site. I added the inlinks, the Quantcast, and the Compete totals. This was then divided by the Alexa rank (divide, because the lower the Alexa number, the stronger the site). Then the computed result was multiplied by the PageRank to get a final "score".
One could certainly make the case that using Google PageRank to eliminate contenders has its flaws, but since Google drives up to 90% of search traffic, and since the SERPS (search engine results position) of what you're searching for is so much determined by PageRank, I felt it was, at the least, an educated starting point.
As can be seen in the table below, digg.com is the clear leader, with del.icio.us running a close second place. Technorati is actually a much stronger contender than I thought it would be. And, for example, while Slashdot sports a PageRank 9, its composite number just doesn't add up to make it even into the top 5.
Now, you may ask, "How can this help me"? Well, from an SEO standpoint, these top 9 sites represent the vast majority of "link juice" you can get. So if you focus on submitting and getting your "Stuff" - your articles, your site, your blog -- into these 9 and forget about the others, you are going to make your SEO optimization job one heck of a lot easier. You'll get a lot more "bang for the buck". Also, it makes it much easier to track where your referrer traffic is coming from.
I present the sorted result for your viewing pleasure: