A mobile user interface suitable for mobile computing devices uses device position/orientation in real space to select a portion of content that is displayed. Content (e.g., documents, files or a desktop) is presumed fixed in virtual space with the mobile user interface displaying a portion of the content as if viewed through a camera or magnifying glass. Data from motion, distance or position sensors are used to determine the relative position/orientation of the device with respect to the content to select the portion for display. Content elements can be selected by centering the display on the desired portion, obviating the need for cursors and pointing devices (e.g., mouse or touchscreen). Magnification can be manipulated by moving the device away from or towards the user. 3-D content viewing may be enabled by sensing the device orientation and displaying content that is above or below the display in 3-D virtual space.