The disastrous rollout of the controversial advertising program -- which alerts your Facebook friends about various online purchases you make, even when you're not logged on to Facebook -- dumped Beacon onto our list. Users initially had to opt out of each Beacon action, instead of opting in. It took a major public backlash to coerce founder Mark Zuckerberg to allow an across-the-board opt-out function. For some, it was already too late -- with tales of holiday gift surprises ruined and extramarital getaways revealed. We trusted you, Mark. We trusted you.