These are tried and tested by me and suit my needs, there may be better ones, let me know if you find a good one. Some of them are paid for, charges are usually low and if they are on this page I recommend the paid for version, but the choice is yours.
I have provided links to the Google Play Store as some of the App names are fairly generic and I am recommending specific Apps.
PasswdSafe – tool for storing and creating random string passwords, the huge advantage of this app is that there is a PC version as well. The encrypted password file/ vault can be dragged from your PC to your phone (or vica verca) and thereby keep both in sync.
Touch Calendar – tool for viewing your calendars, free and paid for versions.
Google Drive – cloud storage and associated word processing and spreasdheets etc.
Exchange rates – multiple currencies can be added; put in a value to one of them, the rest automatically update. Live updates with current market rates.
CamScanner – Take photos of documents, tickets etc via the app and it will clean them up, optimise for viewing or reading, convert to PDF and even OCR (Optical Character Recognition) for text searching. Great for snapshots of articles etc.
Camera Zoom FX – camera app with add on frames and effects available too. Free and paid for versions. As built in cameras get better this may be overtaken as a required tool.
Photo Editor – quite simply the best phone picture editor I have found, does everything you could need on the move including crop, resize, adjust (contrast etc), annotate with text and save as (non destructive to original).
SunSurveyor – sun and moon positions for any location and time; can be very useful if you want to know the best time to be at a given spot.
Voip Calls – (voice over internet protocol). There are 2 parts to this kind of service: an internet Voip account and then a tool to access the account for actually making calls/ SMS etc. I have found the quality of the following to be considerably better than Skype and it can operate more like a normal (fixed land line) phone:
I’m currently using Voipfone for the account side (they offer very good call rates, exceptional call quality and you have a UK local number assigned (or multiple numbers). The service will take incoming calls as messages and email them to you, or calls can be accepted on your smartphone via the interface below.
For the phone application I use Zoiper, which allows access to the above account and has a very simple set up.
Messaging tools are useful if you have international contacts, like an international SMS without the charges. Whatsapp is popular in Europe, Line is popular in the Far East. Both offer messaging as well as sound and video calls from within the app – quality is very good and I have found both to be better than, and less hassle than Skype.
K9 Mail – Simple and effective email client, can hold multiple accounts.
Skype – video and telephone tool.
Social & Blogging
Tweetcaster Pro – can post to multiple Twitter accounts and Facebook.
Travel, Information & Language
Booking.com – check availability, make bookings and store bookings made.
Skyscanner – air fare and routes checker.
CheckMyTrip – Forward airline confirmation emails to this and it will consolidate all the information, you will be informed of any changes and delays.
Maps Me – off line map tool, you select the areas of the world you want (goes right down to street level) and then download them to the phone (advise you store to SD card and download using WiFi – some files are huge), the chosen areas are then available off line so save you roaming charges.
Google Translate – Good place to start with translation. Has speaking mode and off line files for a wide range of languages (saves on data fees).
Dictionaries – Bitknights – Selection of dictionaries.
Thai Pro – talking thai phrase book, free and paid for versions.
Talking Thai Dictionary – the above is great for quick look up and some everyday phrases, but this is the top end of talking Thai dictionaries, expensive, but if you are serious about learning the language its a must.
Starchart – star map, I prefer this to the Google one.
Simon Tatham’s Puzzles – great selection of old style games and puzzles.
Pocket Yoga – keep fit on the move.
Sports Tracker – record and share your activities; will satellite track you on your run/ cycle/ walk etc. Then work out distance, speed, calories etc. You can add photos along the route too.
Poweramp – music player.