Everyone's been hearing about the bird flu lately and the potential of a pandemic. Some people are taking the threat very seriously, but I don't think most of us are too concerned.  On the other hand, it's a fact that there have been 10 pandemics in the last 300 years.  Based on that, you'd have to say it's not really a matter of if but of when.  There was an interesting discussion about this on a recent episode of Science Friday, about the disruptions in that there'll be in the economy, distribution systems, etc. if a pandemic strikes.