Logging in to web sites is ironically one of the most difficult tasks put before our users. Usernames and passwords are hard to remember, and harder than ever to type on the tiny on-screen keyboards of mobile devices.
I like this idea because I don’t actually log in to most stuff very often. If it had fallbacks to SMS or an app that would be nice too.
Take this a step further and imagine a service that was your centralized point of authentication. When you go to a site to log in, it fires off a notification to the service which would let you accept or deny it from email/SMS/app. Once you accept, the original service is notified and lets you in. You’d never need to manage another password. It’s crazy and will never work unless someone like Apple, Google or even Facebook took it on. It’s a big, interesting problem though.