I like how Pinterest shows some content; upon scrolling down, it then prompts for a login/join. This is a good example of immediate engagement because the user is already reviewing the exposed pins, and has taken the action to scroll down. The effort to scroll down clearly shows that the user wants more, and it’s at this precise moment Pinterest presents the login/signup screen.
Using a layer of transparency over the content adds to the user experience. We see through the layer that there is indeed more pins. We want to see what’s underneath. We may even start to automatically try reading the obscured content, simply because, well, it’s obscured. It’s content we are not supposed to have, yet, we can’t resist the urge to see if we can get the content anyway despite the obstructing layer.
