Once upon a time, time capsules were the coolest thing since sliced bread. Sliced bread was likely even included in some, so future generations could also see just how cool it was.

Time capsules faded from the limelight for a while, then enjoyed a bit of popular resurgence around the millennium, and are now slowly sinking into obscurity again.

Before we forget them entirely, here's a look at a few impressive ones that are still out there, somewhere.

Westinghouse Time Capsules
Back in 1939, the Westinghouse Electric and Manufacturing Company thought it'd be a keen idea to make up a time capsule and slap it in the ground during a World's Fair.

It included a fountain pen, alphabet blocks and some examples of art and literature from the time. Also a Sears catalog and a pack of Camel smokes, in case the people of the future don't have enough cancer.

Westinghouse loved the idea so much that they made another one for the 1964 World's Fair, only this time they included much more information about atomic energy, in case future people don't know how to blow themselves up or make super-mutants. Both capsules are scheduled to be dug up in the year 6939, 5,000 years after the first one was buried. Let's hope the guy in charge of keeping track of this in 6939 isn't out sick that day.

Crypt of Civilization
Not only does the crypt of civilization have an awesome name that could easily be stolen by the next substandard "Mummy" sequel, it's also pretty much the most intense time capsule in existence. Sealed in 1940, the crypt is below Oglethorpe University in Atlanta, Ga., and is scheduled to be opened in the year 8113.

The crypt contains about a bajillion things that are still pretty cool in the year 2010, including over 800 classic works of literature stored on microfilm; an original copy of "Gone With the Wind"; and audio recordings of notable figures such as FDR, Mussolini and Hitler, as well as Popeye and a champion hog caller. Man, is the future going to love us.

Among the everyday items that got tossed in were a toaster, seeds, Lincoln Logs, a specially sealed bottle of Bud and a "Negro" doll, which we can assume people seriously regret including at this point.

KEO
Earning a special place on the list is the much-delayed KEO space-time capsule, designed by a French artist and originally set to be launched into space in 2003. Then 2006. Then 2007. The 2010. Now 2012.

The plan is to send it out into space in an orbit that will have it return to Earth in 50,000 years, a mirror of the length of time humans have lived. Here's hoping they get it launched before then.

The name "KEO" was chosen to reflect all mankind as the three phonemes in the word are the most common across all spoken languages.

If you head to the website, you can include your own personal message. The satellite can record up to four pages each from every one of the over 6 billion people on Earth. Make it moving enough and maybe future people will use advanced science skills to bring you back from the dead and, very likely, put you in a zoo.

Also included will be a single drop of human blood encased in a diamond, as well as a map of the human genome in case the future is run by hyper-intelligent squirrels.

Stardust
Not to be outdone by a Frenchman, NASA created their own mini space-time capsule back in 1999. And, in a testament to our culture, it was pranked something fierce.

Originally, Stardust was supposed to send one million names etched on tiny silicon chips out to fly around Mars, gather some interstellar and comet dust samples, and then head back to Mother Earth.

It conducted that mission and brought back a reminder of why, in 1999, asking the Internet to give a list of one million names was a bad idea.

Though it was supposed to only include real names, the tiny chips also ended up hosting Darth Vader, Sonic the Hedgehog, Furby, Count Dracula and Jean-Luc Picard.

Apparently there was also an ad for a porn website, meaning Stardust took the spam email you're constantly filtering from your inbox and made it intergalactic.