There were dueling websites, dueling online petitions - including Martin's parents' Change.org petition to seek Zimmerman's arrest, which got more than 2 million virtual signatures - and a national conversation, or argument, about the merits and implications.
In solidarity with Martin, LeBron James and other famous athletes posted pics of themselves in hoodies. Those went viral, too, and the hoodie assumed a new, charged symbolism.
It was an e-trial. During the trial, Zimmerman's old criminal justice professor, Scott Pleasants, testified in court via Skype. (Trolls messed it up, calling in to his number, prompting the whoosh-whoosh Skype sound and distracting the proceedings.) And the defense's closing presentation featured a computer animation.
New York Times columnist Nate Silver wrote that as of July 3, with the Egyptian army deposing elected president Mohamed Morsi, Zimmerman trial had about 20 times the Google search traffic of Morsi Egypt.
On Friday, as the verdict approached, community leaders such as the Rev. Jesse Jackson pleaded for calm: "If #Zimmerman is not convicted, avoid violence because it only leads to more tragedies. Self-destruction is not the road to reconstruction." Many Twitter users switched their profile pictures to an all-black field, with the hashtag #blackout.
Only seconds after the verdict, Trayvon Martin's father Tracy tweeted the family's first public reaction: "God blessed Me & Sybrina with Tray and even in his death I know my baby proud of the FIGHT we along with all of you put up for him GOD BLESS." Trayvon's brother, Jahvaris Fulton, tweeted: "Et tu, America?"
Hashtags such as #NoJustice and #RipTRayvonMartin trended on Twitter. Many celebs tweeted their reaction, including Rihanna: "This is the saddest news ever."
It's also likely, however, that social media helped moderate public outcry. Calls for lawful, measured demonstration went out on Facebook, YouTube, and Twitter. Tweets, vines, and posts from demonstrations in Philadelphia, New York, Los Angeles, and Oakland, Calif. - showing very little violence - were plentiful.
The trial is over, but the blowback continues. Soon after the verdict, the NAACP posted a petition on its website, asking U.S. Attorney General Eric Holder to review the verdict. Response overwhelmed the website almost instantly, and by late Monday, signatures had topped 600,000 and a similar petition on MoveOn.org was near 293,000.