This great story comes to us via pinboard.in, who woke up one morning to find that:
the Senior Vice President for Bad Decisions at Yahoo had decided to give us a little help.
On December 16th, a slide leaked from Yahoo which announced the demise of Delicious, and Pinboard got slaughtered with traffic as a result. This article, which is somewhat technical, explains in a very engaging way how they dealt with the aftermath of this unexpected boon.
It's a great read. Enjoy.