One of iOS 8's minor new features is Touch ID integration with any app, so apps can be secured with your fingerprint instead of a passcode. Here's a list of the apps that have updated to support it.
More of these will certainly roll out over time, but a surprising number of apps already support Touch ID integration. It's pretty handy too, scanning your fingerprint is certainly quicker than typing in a passcode.
We'll certainly see more of these as time goes on.