Web Analytics for Marketers by Eric Peterson

Eric Peterson has great depth of thinking about Visitor Engagement (from Seachonomics conference, Santa Clara, CA)

He defines An index created from the following, not built into all web analytics tools today:
- depth of visits and conversion rate
- Recency of visits and conversion
- Brand awareness (people search for your brand and come to your site directly. Find how strong is your brand/how indexed it is in different search engines)
- Social media engagement – If they digg your content, its a measure of their engagement with your site/product
- Blog subscription of your content
- Comments

http://www.webanalyticsdemystified.com for white papers.
Today we all look at web analytics, but don’t measure that the user loved your content and forwarded to a friend, or digged it or blogged it. That should all be factored into tie to the same user’s engagement with your site.

Good point, we seem to be tracking user’s digging, blogging, commenting, email forward to a friend as viral play and not factoring into web analytics.

The definition of visitor engagement is unique for your business, egment users by repeat users vs new visitors and track visitor engagement separately.