13. A user-interface method for entering an alphanumeric string, the method comprising: displaying on a presentation device an alphabet arranged into a row of letters; presenting visual cues grouping a series of letters of the row into a cluster of letters to aid in the navigation of the row and the selection of a desired cluster; receiving user actions from an input device to move the visual cues along the row of letters to change the letters grouped into the cluster from a first subset of letters to a second subset of letters, the visual cues moving along the row of letters in variable offsets based on a rate of input of the user actions, wherein the visual cues move by a single offset for each user action in response to user actions entered at or slower than a predetermined rate, and wherein the visual cues move by more than a single offset for each user action and the first subset of letters and the second subset of letters are contiguous in response to user actions entered faster than the predetermined rate; and receiving user actions from the input device to select the cluster of letters to cause at least one of the letters of the selected cluster to be displayed in a string field so that an alphanumeric string of characters selected by a user is presented on the presentation device.
13. A user-interface method for entering an alphanumeric string, the method comprising: displaying on a presentation device an alphabet arranged into a row of letters; presenting visual cues grouping a series of letters of the row into a cluster of letters to aid in the navigation of the row and the selection of a desired cluster; receiving user actions from an input device to move the visual cues along the row of letters to change the letters grouped into the cluster from a first subset of letters to a second subset of letters, the visual cues moving along the row of letters in variable offsets based on a rate of input of the user actions, wherein the visual cues move by a single offset for each user action in response to user actions entered at or slower than a predetermined rate, and wherein the visual cues move by more than a single offset for each user action and the first subset of letters and the second subset of letters are contiguous in response to user actions entered faster than the predetermined rate; and receiving user actions from the input device to select the cluster of letters to cause at least one of the letters of the selected cluster to be displayed in a string field so that an alphanumeric string of characters selected by a user is presented on the presentation device. 18. The method of claim 13 , wherein the presentation device and the input device are included in the same device.