1. A method comprising: collecting, by one or more computing devices, a plurality of information items of a plurality of types relevant to a user, wherein: the information items are collected from a social-networking system; and the user is a member of the social-networking system; determining, by one or more computing devices, a relevance value for each of the information items, wherein the relevance value comprises a product of a rank boosting factor and relevance factors, and the rank boosting factor is based on whether an importance level of the information item decreases as time passes; wherein the relevance factors comprise a time relevance, a location relevance, and a social graph relevance, wherein the time relevance is based on how close a time associated with the information item is to a current time, the location relevance is based on how close a physical location associated with the information item is to a current physical location of the user, and the social graph relevance is based on how close a node representing the information item is to a node representing the user in a graph associated with the social-networking system, the graph representing information contained in the social-networking system; sending, by one or more computing devices, one or more push notifications to one or more client devices associated with the user, the push notifications comprising one or more of the information items sent in an order of their respective relevance values.