Useful mobile applications and websites
It's NOT the advertising. We actually use all this applications by ourselves =)
1. Download the Cyrillic alphabet (кириллица) on your mobile phone... Even if you do not understand it, it can be useful. For example, you can google any sign using it. Or some of your new Russian friends will want to leave you contacts or other information.
2. Yandex Metro (Яндекс Метро). Yandex is Russian Google, it has a lot of useful services developed specially for Russians. Yandex Metro is a subway (Metro) map which can tell you the best route between two stations and its duration. Yandex Metro has English language! There are mobile application and the website.
3. Yandex Maps (Яндекс Карты). I still believe that Yandex provides better maps than Google. Moreover, you can plot the route not only by car, but also by public transport, by walk and by taxi (see below). It's really one of the most useful source of information for tourist! There are also applicarion and the website.
4. Yandex Taxi (Яндекс Такси) or Uber. I don't like Russian taxi-drivers at all! They are very aggresive and their prices are much higher than they should be. They always want to cheat you... Actually, I even didn't use taxi in Moscow before Yandex and Uber got here. Now it's much better - you can just use any of these sites to get taxi, it would be cheap, quick and comfortable. I usually use mobile application, but you can use the website, too. Please, do not use inoffial taxi, it's nor safe, nore cheap!
5. Suburbuan and long-distance trains. Russia is quite big country, so you need to travel a lot to see only its small part! Unfortunately, infrastructure is not so good here, highways are rare, airplane tickets are expensive and there are a lot of places without airports at all. Trains is one of the most popular way of traveling here. You need two resources to use them: 1) tutu.ru for mainly suburbuan trains, 2) rzd.ru - official railroad website - for long-distance trains. However, ticket booking is the art... Hope, I will have time to describe ot in detail =)
6. Kremlin tickets. Kremlin is one of the must-see Russian sightseens. It's very popular among tourists, so it's better to book tickets online.
7. Moscow metro Wi-Fi. Actually, Wi-Fi in Moscow metro is free but you need to watch advertisment each time to use it. With this application you don't need to do it. Just open the program in Metro, that's all. P.S. If you are first time in Metro, you need to log in official metro website, then get SMS code and enter it to back.