Meerkat
Streaming video has been around for years. The problem has been finding people to watch what you stream. Meerkat solves this problem by instantly sharing whatever you're filming with all your Twitter followers at once. Followers that have the app will also be push notified when you start a new stream, and can watch, comment, and interact, all in real time. In keeping with the instant theme of the app, you can't re-watch streams — they're live-only — and while you can save your own streams to your phone, the company doesn't keep any copies, either.