The abundance of security camera footage and images from individuals near the Boston bombing were vital in identifying the suspects. In fact, this article from Slate claims that we need more security cameras now. Privacy advocates, on the other hand, are concerned that we're giving up too much and the use of cameras could be taken too far.
Social Media had an impact on the event as well, but it wasn't all positive. Users of Reddit attempted to take the bombing investigation upon themselves by creating a sub category and posting all photos for users to see and try to identify. However, in the process of this they came up with incorrect names and the police department said they wished people wouldn't do this.