while i agree that most production apps aren't worth sh*t, i've used nanostudio for iphone as an idea sketchpad for awhile. i've never even come close to finishing a track on my phone, nanostudio is by far the most in-depth offering so far. (after rereading this post i want to add that i definitely don't work for them!)
Barring unfortunate accidents the toilet is where I create most of my shit to be fair. On Friday night I had to much to drink and smoke and created some double barreled sick shit. Oh the joy of the bathroom.
Yeahh same here, next to a producer I'm also a beatboxer so I find myself often in places far away from the computer getting inspiration while beatboxing.
At that point I take out my phone to record it so I don't forget.