I write a lot about "in the river" marketing - which is all about leveraging the power of existing, engaged traffic to deliver relevant, actionable messaging / marketing / promotions. You can see lots of examples of in the river marketing done well here.
Here is an example of the contrary.
Yesterday's huge news was Sports Illustrated's investigation of Jim Tressel and his subsequent resignation. The article went viral and filled my Twitter feed, Facebook stream and email inbox. But Sports Illusrated (SI) didn't take advantage of the immense traffic - this was clearly an opportunity to facilitate sharing and drive downloads / purchases of their new paid mobile applications.
This is the mobile experience when you arrive at the article:
Notice the line: "To purchase a digital version of the magazine, go here." First, that language is unappetizing; but more importantly, "go here" isn't clickable.
For some reason, when you view the article within Twitter mobile, it looks much better and the word "here" is clickable and red:
But when you click it, you arrive at a promotional screen that is not mobile aware and therefore not actionable. It should prompt you to download their application or, if you have the app, purchase the magazine version.
In summary: most sites dream of the opportunity to be flooded with traffic. Prepare in advance and make sure that your experience / funnel is primed to take advantage of the flood.... after all, they only happens once in a blue moon.