Speaktoit Assistant is an Android app for Android phones and Android tablets that in many ways resembles Apple's Siri for iPhone 4S (and the less successful Evi for Android). It acts as a virtual assistant that can respond to voice commands and perform web searches and other simple tasks. You can use Speaktoit Assistant to launch apps, find contacts, compose email or text messages, create calendar events, give directions, and more.
Speaktoit Assistant is an Android app that uses Google Voice Search to understand your spoken commands. The app lets you choose from among several iSpeech voices, all of which sound a bit more natural than Google's robotic-sounding text-to-speech (TTS) service. I ended up settling on a female voice with a British accent that I found quite pleasant and easy to understand.
The app has a fun feature that allows you to design a custom avatar for your assistant. The avatar doesn't do anything functional, but it does give the app a bit more personality and puts a face on screen to go along with the app's voice.
Speaktoit Assistant is easy to use: Simply press the onscreen microphone and tell the app what you'd like it to do. Like Siri, Speaktoit Assistant has a sassy personality and will occasionally offer somewhat snarky responses.
But even though Speaktoit Assistant is one of the best and most versatile voice-powered apps for Android I've used, it had some hiccups and limitations. At times I had to repeat my commands multiple times or manually type them in, in order for Speaktoit Assistant to understand me. Also, the app could not read email or text messages aloud--a feature I had hoped would be included.
Still, overall, Speaktoit Assistant is a good voice-controlled app that supports a fair amount of integration with other Android apps. If you want a Siri-like app on your 'droid, this is one of your better options. See also: Best Android Apps