Apps/SaaS that dont cause app fatigue

Is anybody out there working on any apps or SaaS that are "set it and forget it" applications? In other words, they either interact with the user through common channels to the point where they barely realize they are using them (ambient computing) or they are fire and forget with no user interaction.

I think as this "bubble" of SaaS and technology grows, people will become absolutely sick of downloading or logging into yet another interface. I think there is tremendous opportunity there. Thoughts?