One who identified himself as Vinu posted a photostream of the devastation on his Flickr page. Another blogger, Manish, liveblogged the attacks.
Concerned friends and family members, from Bangalore to British Columbia, forwarded e-mails with the url of an open Google spreadsheet that listed the names of the injured and the dead.
Others used Facebook and Google status updates to exchange information and prayers about loved ones.
"If you're a concerned person, Twitter has been great," Anjali Adukia, a Harvard University graduate student with personal and professional ties to India, told ABCNews.com. On her Facebook page, she expressed her concerns for family members and friends in Mumbai and shared the link to a blog that had compiled a list of resources.
Through e-mail, Google status updates and the telephone, she was able to confirm that close friends and family were safe. The instantaneous nature of social media enabled her to correspond with dozens of people at once, Adukia said.
"[The information] spreads like wildfire," she said. "People are hungry for a place to share their information."
But not all of the info churned out was accurate.
The BBC reported that the Indian government had asked for live Twitter updates from Mumbai to cease immediately.
"ALL LIVE UPDATES - PLEASE STOP TWEETING about #Mumbai police and military operations," the forwarded tweet said.
But Amy Gahran, a media consultant and editor of the Poynter Institute's E-Media Tidbits blog, is not convinced that the Indian government originated that message. She has tracked down the original message to a Twitter user named Mark Bao, who is a high school junior based in Boston.
Through his MumbaiUpdates Twitter account, he has been sharing information that is being streamed online by Indian news outlets New Delhi Television Limited (NDTV) and IBNLive.com.
On his Twitter page, Bao said that he had retweeted a message from another person in Mumbai. The specific origin of the message has not been identified but, he said, it has been confirmed by Mumbai police on video that they don't want live updates.
Gahran said the murky origins and genuineness of Bao's message raises questions about the role of social media in emergency situations.
As always, she cautioned, people need to question the source and be wary of repeated rumors as social media gives anyone a megaphone to spread misinformation.
More important, she said it gives people the opportunity to unwittingly spread sensitive or compromising information.
"If someone is tweeting & this is where the sniper is going," she said it could alert the gunman that he is being tracked.
"We're getting to the point where individual people are the media & and governments are starting to get concerned about that," she said.
Bob Gourley, chief technology officer at the consulting firm CrucialPoint LLC and former chief technology officer of the Defense Intelligence Agency, said this is an issue that governments need to seriously consider.
Social media can be very helpful in emergency situations, he said, but it also could help feed information to those with sinister intentions.
"It needs to be addressed," Gourley said.
"Fears of aiding bad guys by enabling leaks of information are grounded in real threats," Gourley told ABCNews.com. "But those threats can be mitigated by training and education, including awareness campaigns aimed at our citizens."
Just as public service campaigns encourage young adults to use judgment when posting personal information online, Gourley said similar campaigns could educate the public about using common sense when sharing information about situations that involve the police and other emergency responders.
But other experts emphasize that social media is just one more feature of our new media world that we need to get used to.
Zachary Tumin, executive director of the Leadership for a Networked World Program at Harvard University's John F. Kennedy School of Government, said that any communication channel can be a threat.
"Twitter's no different. It's how it's used and who uses it," he said. "In the case of the Mumbai attacks, yes, there's been extra activity. Is there a chance that it's compromised attacks? Yes. But is it likely? No."
So much unreliable and unvetted information flows through Twitter, he said, that it makes it difficult to "sort the signal from the noise."
If someone is monitoring their Twitter stream, they'll be inundatated with misinformation, disinformation and real information.
"And God bless you if you can sort it out," he said.