At SEOmoz, our biggest goal is to convert readers into regular visitors. Luckily, through our Indextools tracking software, we're able to see exactly where our signups come from and what search terms and referring domains tend to bring the highest converting traffic. Here's a couple quick examples:

The above chart shows keywords that people came to SEOmoz with, the number of first time vs. returning visitors and the number of actions (in this case, a signup on the blog) those visitors performed. It's clear from these numbers that the best search traffic for SEOmoz comes from visitors searching for our specific site/brand and for SEO tools, although I'm happy to see that visitors searching for "SEO" also convert at reasonably high rates.

The next chart looks at conversions by referring domains, and shows some fascinating data:

I know I pulled a long list here, but I wanted to illustrate a few important points.

Notice that forums like Digitalpoint, SearchEngineWatch, SEOChat and Sitepoint send relatively good traffic, and they're in near direct correlation to my personal participation (and the participation of existing SEOmoz members) at those sites. SEW forums is where I was most active (and probably most visible, since they're closely tied in with the SES conference series). SEOChat and Sitepoint have fewer members that I personally know and connect with, and are lower on the list.

SEOcompany sends us trafifc primarily to the tools, some of which require a signup and hence, the signup ratio is high.

Social media sites like Digg and Del.icio.us are on the list, but the conversion rates from these are terrible (though Del.icio.us is nearly 5X the rate of Digg). Stumbleupon is the worst of the bunch, at 0.03%, but I'm actually surprised it's not even lower, since Stumblers aren't neccessarily in the web sphere, while Diggers generally are more webdev-focused.

The sites where rates are above 10% are generally sites that have pointed to a particular post (or a few) and send relatively passionate visitors who feel inspired to comment. There's also a few that have pointed directly to the KW Difficulty tool, where signup is required.

One of my favorites on the list is videos.webpronews.com, which comes directly from my interview of Vanessa Fox during my stand-in for Michael McDonald. It's one of the highest conversion rate links and yet it points to the site as a whole, rather than a specific post or tool, meaning those visitors had to at least skim through the site and join up - a very encouraging sign that I need to interview Googlers more often :)

The other big referrers are mostly blogs and personal homepages - the blogs in particular (Copyblogger, Stuntdubl, SEOBook) are worthy of attention, as this is the most likely audience to convert to SEOmoz readers, since they're already in the mindset of reading blogs.

If you take the above technique and apply it to conversion pieces on your own site - whether they be signups or form submissions, add to cart actions, checkouts or ad clicks, you can get an incredibly good idea of where your best visitors come from. Conversion data offers even more than what I've shown above - you can refine by entry points, pages viewed, countries, languages, browsers, number of visits and more. I believe that action tracking is one of the most valuable things we do, both for our own sites and for our clients and it's one of the best techniques any website can use to improve their marketing foci.

If you've got examples of action or conversion data that you've used in the past, I'd love to hear about it.

p.s. The above charts come from the last few months of 2006 (prior to that, we hadn't engaged action tracking).