For a while, the idea of social software was something that had to be sold. Although many librarians were experimenting with it, there were a lot of concerns. Now, social software, like Library 2.1, is starting to be viewed less as a disruptive force and more as a regular part of a librarian's workflow. This article highlights a few examples that demonstrate the spirit of Library 2.1. The author presents a handful of practical, mature, sustainable applications that are making a difference for library users.