From the break-in at Lindsay Lohan's Los Angeles home posted on YouTube to missing-person Twitter alerts from the Boca Raton police chief, social media sites are being used to fight crime and make our neighborhoods safer.A couple from Atlanta rigged their house with cameras, and after a burglary at the home, they posted the surveillance on YouTube. Word spread, several people viewed the video, and eventually, police were able to catch the burglars, according to a Christian Science Monitor article. Similarly, video of a break-in at actress Lindsay Lohan's house led to an arrest after the footage was posted on YouTube.The Broward County Sheriff's Office website, Sheriff.org, has YouTube videos that can be shared. A free service called "Cyber Visor" sends text messages or e-mails if there is a crime or security concern in your area.If you live in Boca Raton or Boynton Beach, you can follow and interact with your police stations on Facebook and Twitter, where they post updates of crimes, safety tips and even ask the public for help.Janet Forte, from Miami, is a social media strategist who is using Twitter, Facebook and blogs to blast messages when people go missing. She started doing so after the disappearance of a friend, Lily Aramburo. Forte has thousands of followers on her Twitter account at twitter.com/yogini.Social media can be used not just to report crime, but also to prevent it.Form a neighborhood watch program and, instead of the old phone tree, create an online group using Ning, Yahoo or Google, where you can communicate, share information and get to know your neighbors.Send group messages instantly with Twitter updates and SMS alerts to check up on people, or if you see suspicious activities.If some people in your neighborhood watch group are tech-savvy, they could easily add crime maps, which show data on crimes committed in your neighborhood, and a sex offender locater to identify where accused sex offenders are residing.A great site to search for sexual offenders is http://locator.govisions2020.com/, which allows you to receive e-mail alerts when an offender moves to your area and allows you to send Twitter updates about them.Social media has also become the first place people check during disasters. In the recent Southern California fires, people checked in with loved ones on Facebook, posted photos on Flickr and posted news reports on Twitter. Your neighborhood watch group could serve as a way to communicate with neighbors and get news updates during some emergency situations.And of course, follow and fan the Sun Sentinel on Facebook and Twitter for news updates on crime and during an emergency.Seth Liss is SunSentinel.com's News Community Manager. You may reach him at firstname.lastname@example.org.