Psych!

April Fool's is the Internet's favorite holiday. Some of the better tricks online today -- and what tips you off that they are jokes.

-- Monica Hesse

Gmail Custom Time

http://mail.google.com/

The shtick: A new app allows the perpetually tardy to back-date their e-mail delivery, giving you the appearance of never missing birthdays or deadlines.

The tip-off: Custom Time works because of an "e-flux capacitor." Hmm, Back to the Future, much?

McCain at Burning Man

http://www.burningman.com

The shtick: John McCain plans to bring his campaign to the über counter-culture, mind-altering fest.

The tip-off: John McCain plans to bring his campaign to the the über counter-culture, mind-altering fest.

Dollar Out, Euro In

http://www.virginmedia.com

The shtick: The Department of Monetary Policy has announced that the U.S. will abolish the dollar and do a money meld with Europe.

The tip-off: The head of the "Department of Monetary Policy" is named Flanjingle.

New Tech Products

http://www.thinkgeek.com/

The shtick: Think Geek's products of the day include The Personal Soundtrack T-Shirt, a YouTube tazer, and a USB pregnancy test.

The tip-off: Dude, if these products existed, we'd all have them by now.

TBS Changes Name

http://www.tbs.com

The shtick: TBS has changed its official name to "The Boring Station," and will now feature such shows as "Extreme Data Entry," "ComaCam: Almost Live!" and "The Snail Show."

The tip-off: Still not clear whether this one's a joke.

See any other good ones? Post 'em in the comments.