Dearest Digg,

I couldn't help but notice your site has a small technical issue.  It's no biggie, but I think fixing it could save you some money.  I'm all about saving people money, just the other day I handed out coupons for a free trial-sized bag of bean-lard mulch. I know, I'm practically a saint.

I noticed that digg can be reached through both http://www.digg.com and http://digg.com.  I don't know if you're aware of this, but some of the cool kids are redirecting requests for the www version of their site to the non-www version.   Why would they do such a thing?  Aside from appearances, they're probably doing this because having a single, canonical version of every URL on your site improves your rankings at search engines.

According to Google employee Matt Cutts:

Q: What is a canonical url? Do you have to use such a weird word, anyway?
A: Sorry that it’s a strange word; that’s what we call it around Google. Canonicalization is the process of picking the best url when there are several choices,
....

Q: So how do I make sure that Google picks the url that I want?
A: One thing that helps is to pick the url that you want and use that url consistently across your entire site. For example, don’t make half of your links go to http://example.com/ and the other half go to http://www.example.com/ . Instead, pick the url you prefer and always use that format for your internal links.

Q: Is there anything else I can do?
A: Yes. Suppose you want your default url to be http://www.example.com/ . You can make your webserver so that if someone requests http://example.com/, it does a 301 (permanent) redirect to http://www.example.com/ . That helps Google know which url you prefer to be canonical. Adding a 301 redirect can be an especially good idea if your site changes often (e.g. dynamic content, a blog, etc.).

I know what you're thinking: "I'm Digg, What do I care about improving rankings at the search engines?  My value is based on user generated stories and community!   Not ranking well in that list of ten little blue links when someone searches at google won't cause my downfall!"

I agree, your future doesn't depend on it - but I'm just trying to save you a few bucks.  Remember the bean lard mulch?

I recently heard someone describe Google as "the new http://" -  meaning Google has become the new precursor to information discovery online.   Right now searching at Google for many phrases returns a mixture of www and non-www versions of Digg pages.  While plenty of these pages rank well, having a canonical version could potentially make them rank better.   Wouldn't you prefer it if you showed up in the number 1 spot in the search results instead of 5 or 6?   The difference in click-through rates for the top three versus 4-10 are incredibly substantial.   Click-throughs from Google mean more visitors to Digg from a broader audience.  This audience might be inclined to click on some of your ads, meaning more money in your pocket.

You could sign up for Google Sitemaps and select which version of your site is the canonical one, but there's an easier way.  According to netcraft you appear to be running Apache, so you could easily fix this canonicalization problem with three lines of code in your configuration file:

RewriteEngine On
RewriteCond %{HTTP_HOST} !^digg\.com
RewriteRule ^/(.*) http://digg.com/$1 [R=301,L]

Simple enough, right? 

Sincerely yours,
Matthew Inman
SEOmoz.org