Get Your April Fools' Day Online

April 1st is an unofficial holiday on the Web. A number of sites have revamped their homepages, introduced wild new products, or announced news that seems, well hard to believe. But be wary, it is April Fools Day.

The Guardian is going all Twitter, with all its content to be limited to 140 characters. The newspaper also said that it would rewrite their entire archive going back to 1821, including major stories like "OMG Hitler invades Poland"; and "JFK assassin8d @ Dallas."

Google introduces Gmail Autopilot which will respond to received emails without the user having to open and read those emails. Users are warned that if two Gmail accounts both have Autopilot on, the results decline after a three e-mail messages stating "experiments have shown a significant decline in the quality ranking ... and further messages may commit you to dinner parties or baby namings in which you have no interest."

Meanwhile YouTube served up some upside-down videos on its homepage. To get it to work on any clip add "&flip=1" to the end of the URL.

Reddit re-created itself to look like rival Digg (which has not pulled a April Fools makeover). And Fark's New Fark Experience previews today in the mode of Facebook.

Smellr , "It's like Flickr, but for your nose," was introduced today. A TechCrunch prank, the site features cologne ads with various Web luminaries. TechCrunch also has a comprehensive roundup of the Web celebrating April Fools' Day.

Finally if you need to get away, Expedia is offering " Flights to Mars from only $99 ." Or you may want to drive off in the brand-new " Android Car ," a joint venture between Ford, GM and Google, expected to hit the sales-floor .... not anytime soon.