Here are popular apps that we can use not only for our travel, but for our lives without minding about OSes.
1. Evernote
"Evernote" is one of the most useful notetaking apps. On your phone, you can directly take photos and audio with your notes, and keep them on your phone and cloud. You can keep your itineraries on it. You can add the photos of tickets and documents, clip websites, note the important information, and manage your tasks with the reminder. (Other Alternative: Microsoft OneNote with Office Lens)
2. Kindle App
Everyone wants to read books on board. You may read travel magazines, or your favorite books. Naturally, you can buy books at the airport stores, but you may keep it all the way of your travel. Amazon provides Kindle App for smartphones as a cross-platformed reading tool. If you accidentally replace your phone just before your travel from Android to iPhone or Windows Phone, you can keep reading the same books on your new phone. (Other Alternative: Kobo Books)
3. Skype
Skype is one of the communication apps. You can call and text. Even you are not in your country, you can call to your family and friends over WiFi on your smartphone. Now you can use this with your Facebook account, so this should be more useful than before. Between Skype users, you can call and text for free. (If you call to a land line or mobile phone, you need to pay for a charge. However, it's absolutely less than using a phone card. (Other Alternatives: WhatsApp, Google Voice, Viver, etc.)
Years ago, I wrote about useful services for travel. Recently, some of them were shut down. One of them was "Springpad." Many people have used Springpad for their bookmarks and reminder on their smartphones. This was a big loss for people.
Now I picked these three items because they are relatively stable. Trust me, at least you can use for some years in the future.
(Without these, as your information tools, Tunein (Radio), Spotify(Music), and Feedly (Feed Reader/News/Magazines) are good for travel. You can use over WiFi if you don't have a phone line. Streaming music and radio on your phones may cost you a lot. Please make sure about the limitation of data on your phone plan.)
"The Man Who Can't Be Moved" (2008)
by The Script
Now the season is changing little by little. The winds are cooling down the hottest summer days. Staying with travel friends is very fun, but as long as people who decided to live there, they need to move forward. After cutting up the moments of your travel days on your memory, now you have your own way of "life."