When you google for the best Android apps you get a huge number of lists, each list with a large number of apps. In addition to those lists usually containing way too many apps to be really that useful, the apps are often US-specific, being of no use to 95 % of the world's population. Here's my take on the top 5 Android apps -- these are the apps that I think every Android user would really benefit of:
5. GO Launcher EX. You might not have thought about it, but pressing the home key of your Android device doesn't just "take you to the home screen", it actually launches a home screen program, also known as a launcher. So in your Android device even the features of your home screen are not statically defined but can be changed by installing a new launcher. GO Launcher EX is a versatile launcher program that contains many improvements over the default launchers. For example, GO Launcher EX allows you to resize your widgets to any size you like even if they don't support those sizes out of the box. It allows you to add multiple shortcuts at once and also contains a nice scrollable and customizable "app drawer" at the bottom of the screen. GO Launcher EX also supports scrollable widgets, so Launch-X becomes even more useful. With Launch-X widgets you can squeeze more shortcuts into a smaller space, saving lots of precious screen space. Use, for example, one Launch-X widget for all of your games and another for your best apps, and you'll still have plenty of room for widgets in your main screen!
4. Tiny Flashlight. Ever been in a room with little to no light? Yep. This app lights and keeps on the bright flash light of the camera of your device. You can even install it as a one click widget to your home screen. Always have a flashlight at hand with this app. And even if you don't have a camera or a flash light for it in your device, this app can turn your screen to white and to maximum brightness allowing you to see in its light.
3. OsmAnd. One of the best map programs available. As the name suggests, OsmAnd works primarily with OpenStreetMap (OSM) but also supports Google, Microsoft and Eniro tiles, for example. OsmAnd is special in that it also supports navigation and can even speak the route directions using a speech synthesizer. The program can also download OpenStreetMap vector maps into your device's memory so that you can use the maps offline, for example when you are abroad. Yet another very useful feature is that you can easily find points of interest based on a category. Where are the nearest restaurants or gas stations, for example? OsmAnd can show you. I recommend getting the latest version for free from the OsmAnd homepage.
2. Opera Mobile. A blindingly fast web browser at best, it beats the default browsers in all aspects hands down. Opera Mobile is easy and intuitive to use. It supports multiple tabs and contains a Speed Dial screen to which you can set visual bookmarks to nine of your favorite web pages.
1. Llama. Llama is a Location Aware Mobile Application. Llama introduces profiles and location based events to your device. For example, you might have a profile called "Home" in which the WiFi would be turned on, the ringer volume would be set to medium and the vibration off. Then you might have a profile called "Outside" in which the WiFi would be off, vibration on and ringer volume set to maximum. Llama then knows your location based on the phone masts: you only have to tell Llama that "I'll be in a place I call 'Home' for the next hour" and Llama starts learning the masts. When the learning is done and your phone then connects to a mast Llama doesn't know, it triggers the event "Left home" which switches to the profile called "Outside". Similarly, when you get back home your phone connects to a mast that Llama has learned in the past, triggering the event "Enter home", which switches to the profile "Home". In addition to location, actions can be attached to events such as plugging the device into a charger, entering a certain WiFi network or just on certain times. For example, Llama can be told to automatically completely mute your phone for the night. This is how it should have always been and I find Llama an innovative and extremely useful tool that everyone should have.
This concludes my list of best Android apps. I hope at least a couple of them were new to you and that you find all of them useful. :)
Edit/Add: For some more great apps check the runner-ups I considered for this list!