The megaphone lets you send a message to your less-active friend telling them to go for a walk, run or bike ride -- but you can only bully them once ever seven days.

CNN: Fitness tools that tap the power of your friends

Bookstores were places where you could go to browse the newest books and purchase your own copy to read, lend to a friend, or give as a gift.

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You counsel your friend, then go back to your e-mail.

FORBES: And Now for Something Completely Different: Context Shifting

You see an event your friend is attending, maybe you want to go as well.

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