You have to unlock the phone? Says who?
So think through it logically: This is going to be either an app or a web page. If it's a web page you'll have to have your phone unlocked. If it's an app, there is a potential to use it on the lock screen but 1) that would only be feasible for Android phones, and 2) doesn't work if you're using something like Exchange which prevents lock app programs unless you have rooted your phone.
I guess there is an alternative if were only an image and you made it your lock screen background, but that's going to have some hard buy off from drivers, and will have text in front it that will interfere things.
The only way you're going to realistically do things without unlocking the phone would require modifications from Apple and most smart phone manufacturers, as well as the app creators designing things accordingly.