Voice Control is increasingly being used for website navigation.
Mobile Websites and Mobile Apps feature voice control to overcome accessibly issues and compliment keyboard free navigation.
Examples of Voice Control Systems:
SIRI - Native Voice Control for Iphone / Ipad etc..
VoiceXML - A Markup language used for simple options , more commonly used in automated Business answering services. VoiceXML requires Voice Browser support [like Opera Support].
Webkit Speech is becoming a popular standard for online applications. This requires a Webkit Based Browser such as Chrome or Safari.