1. A method of establishing a multimodal personality for an application that provides vocal and visual output, the method comprising: with at least one processor: selecting, by the application that provides vocal and visual output, matching vocal and visual demeanors; and incorporating, by the application, the matching vocal and visual demeanors as a multimodal personality into the application by rendering a voice prompt and/or response generated by the application in the vocal demeanor and rendering a visual element generated by the application in the matching visual demeanor, the voice prompt or response being rendered in a voice having an age, gender and/or accent based on the selected vocal demeanor, wherein: selecting matching vocal and visual demeanors further comprises selecting a vocal demeanor in dependence upon a history of a user's navigation among web sites, the vocal demeanor being selected to match a visual demeanor determined based on at least one property of web pages previously visited, the at least one property comprising one or more of: text font; count of words on the web page; proportion of white space; ratio of graphics to screen area; or ratio of text space to graphic space.