Yesterday's mail

Email use is on the decline: Recent research shows that visits to email websites such as Yahoo and Hotmail have dropped 6 percent in the United States since November 2009, and 18 percent among 12- to 17-year-olds. Hotmail remains the largest email service (364 million users) and Yahoo is in second place (273.1 million), but Google's email service, Gmail, grew 10 percent last year to 193.3 million users.

While traditional email is still popular with adults, teenagers increasingly gravitate toward instant messaging, texting, and Facebook, through which 250 million users send 4 billion messages each day, an average of 16 messages per user-substantial when compared to the average of six emails consumers send each day. This growing preference for multiple methods of communication may help explain why Gmail has escaped its competitors' decline: The site includes chat, text messaging, video conferencing, and phone calls alongside its more traditional email.

Emergency e-service

When a blizzard buried many Eastern states under at least a foot of snow over Christmas, people turned to the internet for help. One site originally developed to help the Washington, D.C., area cope with last year's blizzards, Snowmaggeddon Clean Up, uses Ushahidi, a tool for creating "crowdsourced" maps based on information collected from email, Twitter, text messages, and the internet. In December, the site allowed residents of New York City and Boston to report a need (ranging from "plows needed" to "power outage") or offer help (such as "snowblower available" or "shovel to share"). The tool also made it possible for residents to organize a "cleanup party" with friends, a church, or another community organization. In Newark, N.J., Cory Booker, the city's mayor, asked residents to report through Twitter which streets still needed to be plowed, and also to report needs-such as having to leave home for a medical procedure. Officials then dispatched cleanup teams to those locations, and Booker himself showed up at several homes with a snow shovel.

Taste test

Internet companies have two methods for recommending products to you. Method one focuses on your actions: Netflix depends on ratings and viewing history, and Amazon on browsing and purchasing histories. Method two measures group taste:

Yelp, Rotten Tomatoes, and Pandora have integrated with Facebook to suggest content based on the businesses, movies, or music that your friends and contacts like. Watch for sites to move to the next phase: blending the two recommendation methods. Let me know (mailbag@worldmag.com) if you feel that a site definitively knows your taste.