This social-media blackout after a mass shooting is not unprecedented for the NRA. The gun lobby didn't tweet for 10 days last July following the fatal shooting of 12 people in an Aurora, Colorado, movie theater.

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Also, they can't liveblog or tweet during their meeting.

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While social media apps were preprogrammed into the buttons, I wouldn't recommend trying to Facebook or tweet on it while gaming on the big screen.

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In her first Tweet after the game, Webb didn't mention what had happened.

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The TwitterPeek essentially presents a stream of Tweets as if they were the subject lines of emails, so when a new Tweet shows up in your updates, you don't just read it -- because it's been truncated.

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FitBit also has a leaderboard but doesn't currently allow messaging through the mobile apps, though you can tweet out your progress.

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But there is a risk that companies will concentrate on a handful of activists (who tweet a lot), while neglecting average customers (who don't).

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The last entry on his site was a two-day-old tweet that read "1 month till my first race of 2013.. Can't wait to burn it up!"

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