What are your favorite music related phone apps?

Spotify...love it, and yeah I know artists dont get squat from them but at 10 bucks a month and as much as I listen music I love it...and most of the stuff I have saved in my library is stuff I have bought on cd or record but can't play that on my cellie while riding bike.

 

Caustic music creation with cool synths, a sampler and vocoder. On both iOS & Android. Free version for PCs
Mobile Sheets Pro. Organize pdf and jpeg charts. Runs on Android phone. iGig is more popular but is tablet only. For Score app is very good has similar functionality for iOS only
iReal Pro. My Favorite. Download and create Chords charts and includes a play a long function . lively forum has searchable function with chords for most genres. iOS & Android

 

I like the following (for Android):
-Perfect Ear - a training app for intervals, scales and so on.
-TE Tuner - a metronome, wave analyser, tuner, tone creator all in one.
-Bass trainer - used to test how quickly you can identify the position of notes on the bass clef (I don't use this as frequently now, as I just avoid looking at the tabs unless they're all that's available)
-Songstrrr - lots of music tabs available which scrolls slowly as you're playing.
-Metronomics - useful for [trying to]nailing complex subdivisions.
-Electrum drum machine - produce your own drum rhythm, and then send the output through bluetooth enabled speakers.
-Deezer - i used to have a free subscription with my mobile phone network but that ended a few years ago. I still use it because i have shed loads of playlists on it such as artists to check out, songs/albums to checkout, favourite artists, and all my faves categorised into their genres and subgenres like a filing assistant with OCD.
-XiiiaLive Pro - no longer actively supported but still gives the best sound with it's built in equaliser (maybe I nred to update this to something better and that is actively developed).
-Soundhound - used to identify(title, artist, album it appears on, when produced, etc with links to the artists etc) unknown songs while they're playing. Open the app, press button, and all the info is there for you within seconds. Can even identify really obscure tracks.