Siri and Cortana may get more attention but Google Now is a fantastic Android alternative that gives you access to a huge amount of functionality just by saying 'Ok Google' at your phone. You can compose text messages, do Google searches, set alarms, create calendarentries and much, much more, and the voice recognition has come on leaps and bounds in the last few years.
And Google Now is set to get even more useful in the coming months, as the software is opened up to third party app developers. According to the Android Developers Blog, you'll just have to add a few lines of code to enable the functionality for search on your app. That means from your Android home screen you'll be able to kick off complex searches like - 'Ok Google, search pizza on JustEat' or other things that contain less calories.
It's another step in bringing the Google eco-system to everyone, all the time but instead of forcing it down our throats the company is keen to integrate their software and services in a way that's genuinely useful for users.
So expect to see this popping up in other apps very soon - though you'll have to be running Android Jelly Bean or higher and speaking English for it to work at the moment.