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Personalization and humor are two of the ingredients marketers might want to stir in when attempting to whip up a successful viral campaign.
Perfect example: CareerBuilder's Launch of Monk-e-Mail.com last year allowed users to record a message and send it to friends through the voice of a chimp - and generated some 85 million Monk-e-Mails in all, writes USA Today. CareerBuilder is betting its new Age-O-Matic.com, which allows people to alter their age by 50 years and email it to friends emphasizing the stresses of a bad job, will be just as successful as last year's.

Launching on Tuesday night's premier of American Idol, M&M's promoted the "character creator" on its new BecomeAnMM.com site. Users can create, in Mr. Potato Head fashion, a likeness of themselves to which 34,000 showed up to spend an average of 11 minutes making characters.

And finally, the holiday favorite, OfficeMax's ElfYourself site totalled 11 million elves between Nov. 27 and its close on New Year's. At its peak, more than 41,000 elves were being created every hour. Members of the Today Show even built elves, and the Cleveland Cavs even elfed their mascot and put it on the bigscreen during games.