This article is 💩 mammoth shit
This means its value is not in informativeness, but in memory of how it was
There may be an update at the end of the article. Or maybe not.
In this note I'll try to tell you what interesting, and most importantly, useful apps for Czech Republic I found for Android phones. I use some of them every day, some less often, but they all make life much easier. Unfortunately, Google Play is quite a dump, so it's better to install verified apps than to look for a needle in such a haystack.
I recommend reading a similar article from Ilya on podebrady.ru. Perhaps there you'll also find the information you need.
First of all, I'd like to note that the Czech language, or more precisely, the Czech keyboard layout, is slightly different from the usual English one. Accordingly, for convenient use of all services and sites in Czech Republic we'll inevitably have to install the Czech keyboard language (read about adventures with computer keyboard).

I assume you should install the Czech layout instead of English. To do this, we should go to settings - language and input - input languages, and there remove the English layout and enable Czech. Menu names may differ, but the logic is about the same. It will all look like in the picture. To write Czech letters, you need to hold down the similar English one and select the needed symbol.
Let's go through apps - navigation first.
Pubtran

First of all we need the pubtran app. With it we can easily find a route from any point to any other. You can see the price, schedule, delays, and different options - there are both bus routes and rail routes. An indispensable app for those who move around the country at all.
Upd. 04/02/2015
Still using it. Sometimes lags, have to use an analog - czech timetable.
mapy.cz

For viewing the Czech map I use the mapy.cz app. Excellent maps from the local search engine, Google killer - seznam.cz.
The maps show current location, leisure places, cafes and much more. In general, must have. Unfortunately, works poorly without internet. The ability to download maps directly to the phone exists, but full use doesn't work. In any case, with proper use - indispensable.
Upd. 04/02/2015
Using it, big plus - offline option
Prague city guide

Next I'll tell about an app for those who want to walk around Prague specifically - Prague city guide (from tripadvisor).
In it you can see many cafes, restaurants, hotels, shops - in general, everything. All this is accompanied by reviews, stories, photos, and most importantly - maps. A big plus of the app is that it works without internet, but it needs to be updated frequently (this can be done at home). On the other hand there's also a minus - the program is only in English. I don't think this will be a problem for anyone, so at least it's worth checking out.
Upd. 04/02/2015
Not using, little point
Maps with me

Worth mentioning offline maps - Maps with me. There's also a Czech map, but I don't use this app often - there hasn't been much need yet. But at least it's worth knowing about it. Too bad the full version is paid.
Upd. 04/02/2015
Use extremely rarely, when mapy.cz didn't help
metro24

And finally - Czech metro map - metro24. Unfortunately, this program is paid, but I think it's not a problem to find a cracked version (which I'm not calling for, of course 🙃), but the developer is from Russia, so you can support them. The program is quite convenient and simple, you can easily find maps for other cities. After installing the program, you should also install the Prague map itself. You can calculate travel time, correct transfers. Convenient, in general.
Upd. 04/02/2015
Using it, but over time the metro map has also been deposited in my head :)
Now about translators and dictionaries.
Google translate

In first place, of course, is the well-known Google translator - translate. It can translate both pieces of text and individual words. Can also recognize photographed text. Can read aloud. Recently the ability to download dictionaries directly to phone memory appeared, which means that formally the app can work without internet.
Upd. 04/02/2015
Using, but rarely - better to use dictionary for individual words, and translate sentences with your own knowledge.
colordict

Next I'll tell about another important dictionary program - ColorDict.
This program can work with StarDict type dictionaries, read more here.
The program's capabilities are unlimited, whatever you download, that's what you get. You can download my dictionary collection specifically for Czech - then all files from the archive need to be thrown into the dictdata folder, which is right on the phone card.
Works well, can understand words without hooks and checks, can show noun declensions, which is very important in the first time of learning Czech.
There's also a paid alternative - GoldenDict, but the free one is enough for the first time.
Upd. 04/02/2015
Use constantly
Total Commander

The name is quite famous to those who are not sitting at a computer for the first time. It's an ordinary file manager, an analog of explorer on a computer. With it it's easy to perform any important tasks with files and folders on the phone - moving, deleting and others. There are tons of analogs, in principle, you can install any - the functionality will be similar. I chose this one only because it's famous.
TuneIn Radio

To learn Czech, you need to hear live speech. Since you can't talk to people right away, you can listen to speech on radio and television. TV immediately falls off - there's none in the dorm. And in general, it takes a lot of time. As for radio - I caught several stations, quality is good, but mostly all stations are musical (which is also not bad).
There's an alternative - TuneIn Radio. This is the most popular internet radio. There's a choice by genres (conversational, musical), by languages, by countries - everyone will find what they need. The program is super useful for people learning languages, and just for those interested in news.
Upd. 04/02/2015
Rarely launch
Unicredit bank

I use it simply - if I'm lazy to log in from computer, I can log in from phone, quickly check balance, card transactions. By the way, almost every bank has an app for phone, so most likely everyone can install what they specifically need. Usually such apps have ATM search, account work.
Upd. 04/02/2015
Not using. Switched almost completely to Czech bank.
Můj Vodafone

If you followed the advice on podebrady.ru, then most likely you have a SIM card from Vodafone.
For convenient balance viewing, payment, package activation there's the Můj Vodafone app.
Upd. 04/02/2015
Using, useful
Currency

For any foreigner abroad, it's always important to know the exchange rate. It's worth knowing at least to make purchases on time, withdraw money, and just plan the budget.
To help with this difficult task there's the Currency program. It allows you to update exchange rates, monitor trends. Occasionally worth checking.
Upd. 04/02/2015
Using, fortunately in RF they're trying hard to maintain the relevance of monitoring the ruble exchange rate :)
Family Budget

As I said, abroad (and not only), you should monitor the budget, or rather, your expenses. You should always save and try to buy less completely unnecessary stuff.
The family budget program will help us with this. You should get used to recording every expense, even small ones, after each spending, in order to later analyze expenses, for example, for a month.
It will help in future life, I guarantee it. By the way, it's especially good for yesterday's schoolchildren to do this - the program works simultaneously in several operating systems, there's an opportunity to observe a person's actions remotely.
Upd. 04/02/2015
Use constantly, very convenient
Diary

And finally, I'll tell about a program for students and schoolchildren - diary.
This is an app where we can monitor our schedule, homework, write down teachers' contacts and much more. The program is easy to use, there's also a free version. Very good to use at first - you have to move from classroom to classroom, different teachers, and so - everything in one place. For example, in the picture on the right, you can see my schedule for 1.11.13.
Upd. 04/02/2015
Not using, schedule is in the university's educational system
In conclusion I'd like to say that the list is not complete at all. I deliberately didn't talk about such programs as skype, vkontakte, instagram - everyone has known about them for a long time. It's advisable to use them as intended and not waste time :) As new interesting apps appear, I'll add them to this list, but for now that's all. Thanks for attention!
Upd. 04/02/2015
Akční ceny
Program for tracking current prices and discounts in Czech supermarkets. For those who like to save money.