Information cascades are phenomena in which individuals adopt a new action or idea due to influence by others. As such a process spreads through an underlying social network, it can result in widespread adoption overall. Here we consider information cascades in the context of recommendations and information propagation on the blogosphere. In particular, we study the patterns of cascading recommendations that arise in large social networks. We review recent studies of cascading behavior in product recommendation networks, and information diffusion on the blogosphere. Next, we examine theoretical models of information, virus and influence propagation. Last, we present developments on selecting and targeting nodes in networks to maximize the influence or detect cascades and disease/information outbreaks effectively.