San Francisco, California (CNN) -- What do you do if your favorite baseball team is crowned national champion, sweeping much of the city into an alcohol-fueled frenzy?
For nearly 300 San Francisco residents Monday night, their first instinct was to check in on Foursquare.
The San Francisco Bay Area has long provided a suitable petri dish for online services that enable over-sharing. It's recently been the breeding ground for Blippy, a social network that automatically publishes what you charge to a credit card, and Foursquare, a fast-growing mobile-location service for telling friends where you are.
The latter lit up when residents poured into the streets after the San Francisco Giants' first-ever World Series title, over the Texas Rangers. (The Giants have won previous World Series, but as the New York Giants.)
Smartphone-toting techies created a few separate pins on the map to organize the chaos. The most popular was a makeshift venue called "Giants Riot On Polk St!!!"
People on that page chimed in with tips, a staple feature of the site. Some gave a virtual wag of the finger, while others egged the demonstrators on. "Pick up cars!" wrote someone who goes by Sarah W. "Set things on fire!"
That they did. A live video stream from the scene of one of the intersections where people had congregated provided a window to an impromptu bonfire. The video, hosted on Ustream's website, attracted a consistent audience of more than 400 after midnight Monday.
Many more followed along using an online audio stream scanning police communications.
More than 15,000 people listened in on the stream, with about 1,500 tuning in at any given time Monday night, said a spokesman for SomaFM.com, the website that hosts the scanner. That link quickly made its way around Twitter.
The Twitter chatter was organized using what's called "hashtags." Tweets documenting what people heard on the police scanner, saw out their windows or witnessed on the streets included the tag "#sfscanner" or "#sfriot."
Those two terms were the most popular topics in Twitter's San Francisco network around midnight Monday. "#Sfriot" was the second-highest trending topic in the U.S. and third worldwide during the same period.
"This is why we can't have nice things, SF," wrote Mike Monteiro in a popular tweet.
With practically every upturned garbage can or broken car window documented, police could rummage through Twitter to piece together what happened. Photos uploaded from the event are laid out neatly on a search engine called PicFog.
Tech blog Mashable, a CNN.com content partner, published a photo of what looked like a man setting a city bus on fire.
Six people were arrested Monday night, the Los Angeles Times reports. Police officials didn't immediately return requests for comment.
An incriminating tweet or check-in could potentially be used against people who were arrested. But it's unlikely that police would dig up evidence online to go after more people, said Robert Talbot, who runs the Internet and Intellectual Property Justice Clinic at the University of San Francisco School of Law.
"These days, I think reasonable expectation of privacy is shifting because of social media," Talbot said. "If people go on social networks without taking privacy precautions, it seems to me that they're vulnerable."