Facebook wants you to discover all of the cool things that you can search for using the new Graph Search - so much so that they're testing a link that will generate a new, random Graph Search query every time you click it.
Some users are seeing a "Browse" link in the "Favorites" section on the left-hand side of their homepage. This is where you find it with the old news feed design. We can't seem to find it anywhere within the new news feed design (which has only been rolled out to a very small fraction of users).
Clicking on "Browse" directs users to facebook.com/discover-something-new.
It generates a random Graph Search query, such as "Favorite book of my friends," "Places that my friends visited," "Video from my friends' favorite TV shows," and "Musicians liked by people who have interests similar to me."
It's rather addictive, actually. There's a seemingly limitless amount of unique searches that Facebook will generate for you. If you're bored, you could definitely kill some time with this.