I predict that years from now, the launch of Krugle will be used as the textbook example of how a startup can leverage the power of the blogosphere to become successful.
Krugle is the pioneer of a new type of search engine designed by programmers for programmers who are searching for open source code. For guys like me who don't want to reinvent the wheel and want to build applications quickly, open source - and building upon the open source works of other programmers more talented than I - is wonderful.
Don Thorson has a great descption at http://donthorson.typepad.com/don_thorson/2006/03/krugle.html, but while Don makes it sound like everything took off with a bang at DEMO, I can tell you that Krugle was receiving a huge amount of attention before that. In January, Shel Isreal was talking about this remarkable story on the Naked Conversations blog.
The lesson for all of us is that it is possible to gain exposure by leveraging new mediums and methods instead of relying upon the traditional - and expensive - marketing tools such as advertising or even PR.