This is one thing Windows Mobile 7 just killed. Putting stuff kind of off screen, near the edge, discoverable using touch but not buttons or anything. (Android’s version is the long-press which I fault for being a nonhuman vector. Short to an old person or a first-timer is long to the OS; creates “how did I do that” moments like the classic Windows context-menu insanity.)
But these cool WM7 screenedge things are visual and not cluttery. Apple agrees.