You just bought Nexus 4 and you don't know anything about Android operating system, so I will guide you through literally first steps on this great phone.
A really useful feature in case you want to receive a warning notification before you use all of the mobile data available according to your mobile provider contract. It's a great way to avoid additional charges.
Google now is sort of an intelligent personal assistant that depending on the data that Google gathers knows you pretty well. One of the coolest functions of Google now is the voice recognition functionality.
Samsung Android devices such as Galaxy S2 or S3 come with a cool app called Kies Air, enabling you to connect via WiFi connection and manage them using a web browser.