Serendipitous searching happens when your quest for information on a particular topic leads you unexpectedly to find something interesting — whether or not the result is connected to your original query.
The Internet makes it much easier to experience this type of searching.
I decided to search for the phrase "serendipitous searching" to find out more about the topic and not only did I find definitions and examples, but also I found Banana Slug, a wonderful tool that promotes serendipitous surfing by adding a random word along with your search topic or phrase. I found the site mentioned in a boingboing entry. Boingboing bills itself as "a directory of wonderful things."