For learning, not much at the moment:
http://www.studybass.com worked really well for me as a best structured method of working on the bas(s)ics that many self taught muso's don't really spend time on.
Coursea have a list of courses you can 'audit' (follow) for free, but not participate). I did a few back in the day when ya could participate for free - the deadlines are useful for getting things done! The Pat Pattison songwriting one was awesome, but I see it's no longer listed.
I like Paul David's - mix of learning and guitertainment. He's got a beginners course coming out soon, interested to see how he approachs it
bossanovaguitar when learning a bit of Bossa Nova.
Cover Solutions for bass and guitar covers. Playthrough style with tabs - works for me.
Center Stage Guitar, Bass, and Ukulele Academy - for a mix of bass.guit & uke lessons and covers. Simple video's, minimal yak-yak, easy to grasp.
Recording Revolution - Home recording/Songwriting/Production, Good intro to the basics of recording and beyond. He's got a community going, fun to follow his work
Produce like a Pro for recording, I really like the sense this fellow talks. Sometimes a bit over my head, but he know's his $#$!
Quist - Jazz n blues backing tracks and jams. Like that there's song charts to follow in some jams.
Justin Guitar - Enjoying the stuff he's doing with Lee Anderton (Rut Busters/Private lessons).
Not much - the phone's too small for me to work with. I'd really need a tablet to work with recording apps and the like.
Boss Tuner - simple, minimal ads, lightweight install
n-track - loads of features, works quite well. But a pita on a small screen - same for all recording apps I reckon.
Sound Meter - db meter to check I'm not bothering the neighbors