Recently, I read that a blog where I've commented, Lifehacker (and others in its network), was compromised by a group of hackers from a site called 4chan (don't look it up, trust me).
The reason? The staff of this blog network, in an internal group chat, insulted 4chan.
Let me back up. For those unfamiliar with 4chan, it is a message board site with a number of "imageboards" (image-based message boards) on varying topics ranging from innocuous hobbies to drugs and pornography. Needless to say, it tends to attract the worst sort, and is somewhat infamous for its misguided "activism" efforts to bring several websites offline (most recently any website that has ended support for Wikileaks --- a whole other can of worms.)
This most recent instance shows rather clearly the danger of power in the hands of the immature: feeling their internet pride somehow damaged, 4chan mobilized to assault the Gawker blog network's internal blog system.
But in this vengeful drive, these internet crusaders seemed to forget about all of those (myself included) who have now become, frankly, collateral.
Had the group simply attacked and breached Gawker's security, it would have been offensive. But they've gone further --- they've published and mass-distributed the usernames and (weakly and unsalted) hashed passwords of all commenters on Gawker's site, going so far as to decrypt them and compile a list of "stupid passwords", mocking their victims.
There's an old saying that says "when you go for revenge, you must dig two graves." In this case, two graves are not nearly enough.