Taxi: Gettaxi
You can save plenty of money if you dowload this service. You can choose English in settings.
Translation: Google translate (https://translate.google.com)
Russian people hardly speak English. If you would like to ask how to get somewhere, or you are confused about choosing your meal at the restaurant, definitely use this app. The service will give you a very precise translation and also you can hear how does it sound in Russian. You can eighther read by your self or push the bottom and the programme will tell the phrase for you. The result: you are happy and relaxed.
Use eigther online translation or downloud the app Google Translate
Google Map
All Russians use this app, because it is very convenient. You can write down the address and you will have several options how to get there: by car, by public transport, on foot. Very useful for travellers.
Whats up/ Viber/ Skype
Of course you know this applications very well. Make sure it is set up on your phone. That would save you plenty of money while you communicate with your friends and family: calls, messages, photos, videos, everything is free of charge. Very easy to install!