1. A method of reminding a user, with reminder sent to a mobile computing device, to access content on another computing device, such as a desktop computer, when the mobile computing device detects proximity to the other computing device and customizing content accessed with the other computing device based on the reminder, the method comprising: sending, via a network, with one or more processors, content including a plurality of content items; after sending the content, receiving, via the network, with one or more processors, an indication that a user is to be reminded of a given one of the content items based on interaction with at least some of the content items; determining, with one or more processors, a geolocation at which the user is to be reminded and a first computing device both to detect the user's presence at the geolocation and upon which the user is to be reminded; receiving, with one or more processors, from an application executing on the first computing device, an indication that the user is at the geolocation; in response to receiving the indication that the user is at the geolocation, with one or more processors, sending the reminder to the first computing device or accessing a reminder previously sent to the first computing device; correlating the reminder with a request for content based on a list of device identifiers stored in a user profile; after sending or accessing the reminder, customizing, with one or more processors, content based on the given one of the content items for which the reminder was sent; and sending, via the network, with one or more processors, the customized content to a second computing device, different from the first computing device, such that the second computing device receives content customized as a result of the first computing device detecting that the user is at the geolocation.