I'vRead is a service for keeping track of what books you've read. Seems simple, but it can be rather useful for those of us obsessed with reading like myself. Its web site offers the service for free, and using it is already pretty simple. There isn't even another account to register for. All a user needs to do is add a specific tag, @ivread, to a Twitter post mentioning the book. It allows for some basic searches of the data on their website, but the I'vRead API is where the service really shines.
Being, an iOS app that allows users to browser Instagram as someone else, has had its access to the Instagram API cut off. In the first week following its launch, Being reached the Best New Apps section of the App Store's front page and was used to view more than 500,000 Instagram feeds.