I signed up for Yammer with the re-assurance that I would be in control of my company's data. And that the service could be cancelled at any time. Having to make TWO phone calls to cancel my account for a web-based system is absolutely inexcusable, unless it's 1995. The experience took me from mildly unsatisfied to livid in record time. I ran, not walked, away from Yammer after that.