Looking for a very simple way to segment online visitors into actionable segments?
Take any visitor who arrived at your website within the past thirty days following a paid/natural search via Google.
Store this fact as a Yes/No attribute on your database.
Now analyze your catalog, e-mail, online marketing, and retail marketing activities against your usual set of analysis segments --- overlaying the "Google" factor on each segment.
I promise you will learn something about your customers, and your marketing activities, that you didn't previously know.
Go ahead and expand upon this idea using other referring URLs identified in your clickstream data. Again, I promise you'll learn something actionable about your customers you didn't previously know.
Some folks are really doing sophisticated stuff with this information. We can all benefit by starting with such a simple attribute, a yes/no indicator, and then work toward complexity from there.