apps
, smartphone
, must-have
Most used, not most useful, or best ... that would be subjective and much less interesting ;)
One per answer, vote for those that you use.
If you are adding an answer, please indicate what features the application has that make you use it, also include a link to the application's site and a screenshot if relevant.
Probably because it's texting for the 21st Century, and makes complete sense on a phone as a result.
AnkiDroid, a flashcards app for Android.
I use it to learn Japanese vocabulary whenever I have a minute free.
HippoRemote for iPhone.
HippoRemote is a great app that will allow you to remotely control a computer(Linux, OS X, and Windows support) via a VNC connection. The more expensive versions of the app come with profiles for using a variety of common applications such as Chrome, Firefox, iTunes, VLC, XBMC and many more. I use this as a remote for my XBMC media center and it is invaluable.
Remember The Milk best todo app around?
Gowalla & Foursquare on my Android, fun games
WeFi - Great for finding high speed wifi on the move for a laptop that isnt tethered
Cashew, helps me keep track on my spending, has some cool report tools and supports multiple currencies.
Locale for Android, $10, very handy, changes ring/alert volume based on things like location, time of day, plugged in, who it is (another $1 to add SMS related alerting, many, many plugins to extend it), etc. So, at work, things are a bit muted, an home, sleeping time, plugged in, very muted, unless the alert system pages me for work, or the other on call people call me, then extra loud. I love not missing calls because I forgot to turn the ringer up, or being woken (I worked a swing shift) because I forgot to turn it down.
C:GEO geocaching app. You're never far from a hidden geocache, and with c:geo I can log finds on-the-road without any preparation.
Sports Tracker, track my sports realtime.
Gravity for Symbian - excellent twitter (& facebook/4sq) client, I often use it in preference to a desktop client even when sat at my desk. NB Screenshots on the linked page do not do the app justice on a modern device.
Baby ESP (Eat, Sleep, Poop) -- as of writing, my son is 1 month, 1 day old (it says so, right at the bottom of ESP). My wife and I use this app to track feedings, diaper changes, medicine, sleep patterns, etc. We each had to pay the $3.99 but the sync feature make it well worth it. The feature-list is great, development is on-going, and support is fast.
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