The first is Vlingo Virtual Assistant, which is a free app with ads or $2 to remove the ads. It has more than a million downloads and the app is one of the best by some accounts. You can voice dial with the app, send texts, and emails as well as conduct local search. Sonalight Text by Voice is the next app and it will cost you $20 per year. It lets you text using your voice and reads them back to you too.
Google Voice Search/actions is the next on the list and it is free. You can access this by clicking the mic button on the keyboard. The fourth choice is Edwin, Speech-to-Speech. This gives you voice control for different features and you can ask it odd questions since it works with Wolfram Alpha. It is free as well. The last is Speaktoit Assistant, also free. This app is like Vlingo in functionality and has an avatar on screen you talk to.
The only thing that was major about the unveiling of the iPhone 4S was the new Siri voice assistant service. All the other stuff about the iPhone 4S was just not that interesting. If you are on an Android phone and like the idea of Siri, several apps out there will give you similar features right now. Extremetech ran down the top five Android apps that are like Siri, see what you think of their choices.