I'm pretty sure I've said it before, but it bears repeating: be kind and civil in cyberspace. Please. As more and more of us socialize, do business, and conduct a lot of our lives online, the habits and the courtesies you do (and don't) extend to others will definitely follow your name and online presence.
Why am I talking about this? Recently, on a loop I belong to, one member repeatedly called out other members for not participating, not carrying their weight, etc. In a snarky tone. To me, this is simply uncalled for. People participate in online social networking in a variety of ways and to a variety of extents. What one member can contribute may not come close to what another can. Yet the negative attitude is uncalled for, regardless. There is no faster way to turn off people in your social group/work group/etc. than to convey a nasty tone online. And remember that because people can't see your face or hear your tone of voice, they can't tell if (or whether) you're being sarcastic.
Many (most) of you out there are Internet savvy when it comes to communicating with others, I know. And 95% of the social interaction I see is positive and wholly supportive, especially in my various author groups and loops. But every once in a while, temper or attitude creeps in, and then all too soon the conversation takes a turn for the worse.
Please, please, please don't be that person. Consider your words carefully before you post them online for all to see. It's too hard to take them back after you hit "Send."