Economies of scale and advancements in wide-area wireless networking are leading to the availability of more small, networked mobile devices, placing higher stress on existing mobility infrastructures. This problem is exacerbated by the formation of mobile crowds that generate storms of location update traffic as they cross boundaries between base stations. In this paper, we present a novel aggregation technique we call type indirection that allows mobile crowds to roam as single mobile entities.  We discuss our design in the context of Warp, a mobility infrastructure based on a peer-to-peer overlay, and show that its performance approaches that of Mobile IP with optimizations while significantly reducing the effect of handoff storms.