UmairHaque : So the Snowball Effect is not not about Blair Witch (etc) style buzz - it's about value itself snowballing. In fact, Snowballs are a hyperefficient strategy for value creation in a world of connected consumers, but we won't get into the how and why here.
Essentially, once someone (who has a bit of attention) says something that a lot of people agree with, or starts a project that a lot of people want, more people will join in. And this can accelerate. Snowballs are presumably groups or ideas who's rate of growth / adoption is somehow proportional to the number of members or people adopting them.
It's another NonLinearEffect in the modern economy, exacerbated by communication networks. (May also be constrained / enabled by the structure of those communication networks.)
See also :