Saying a nice greeting to everyone is the best way to catch someone's attention.
If that doesn't work usually it's best to address someone with a question.
For example, to ask someone a question you may want to use this format to do it and to talk to others the same way: Person's name: Your question Most of the time you will get someone's attention this way.
The EFF points us to the news of the Philippines signing into law the Cybercrime Prevention Act of 2012, which has a number of interesting and worrisome provisions.
The EFF, quite rightly, focuses on the fact that it makes online libel a criminal rather than civil offense, which could lead to jail time.