Photo: © 2009 Jupiterimages Corporation

A chance encounter in the real world—whether on the street where you live or in a café far from home—can make for a great story. A chance encounter on the Internet, however, doesn't quite conjure that same Eureka! magic. It's not just because of all the phishing schemers and anonymous weirdos lurking around. You lose the cinematic sweep of a real-life run-in because it’s a chance encounter lacking for chance: Facebook exists to facilitate awkward e-mail reunions with dimly remembered grade-school compatriots, and no one wanders into an online forum by happenstance. Yet, we’ve found six destinations that invite serendipity into your office, kitchen, or wherever you chance upon some WiFi.

Trip to Bountiful: StumbleUpon.com

For the closest we've come to a true online chance encounter—right down to its name—try StumbleUpon, which is like having the entire Internet on carefully curated shuffle-play. Click on as many categories as you like ("Astronomy," "Beauty," "Gardening," "Photography"...) and download the site's toolbar (which is admittedly a little irksome—to make it work, I had to switch from my elderly laptop to my husband's snazzy Mac), and StumbleUpon will begin drip-feeding you an addictive stream of sites. Less than an hour after I'd set up my account, I'd already StumbledUpon the following:

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• An online tool that lets me use my mouse to create Jackson Pollock–style paintings
  
• A collection of Albert Einstein quotations ("The secret to creativity is knowing how to hide your sources.")
  
• A photograph of an enormous tiger hugging a man
  
• A series of astonishing trompe l'oeil frescoes by an artist known as Sidewalk Chalk Guy
  
• A prototype for an underwater home (a "submerged dwelling environment," actually)
  
• A database of free text-only books available for download
  
• A list of "Things That Are Not in the U.S. Constitution" (executive orders, judicial review, paper money...)
  
• A compendium of "Unusual Hotels of the World"
  
• The Economist's wide-ranging "Country Briefings" page, and
  
• A video of baby pandas frolicking at a playground in Korea that I watched approximately 187 times before sending it to everyone I've ever met.

My point in making this list (which is in no way comprehensive) is simply that StumbleUpon is the greatest thing ever invented. The site makes the Internet—and by extension, the world—seem both bigger and smaller, infinite in its possibilities yet totally accessible. Warning: I have gotten lost in the wilds of Wikipedia and have fallen down many a YouTube rabbit hole, but never has a website hijacked my brain, my attention span, and time itself quite like StumbleUpon.