I'm glad you're posting this. I've been using Medito for about three years now. In our world of everything costing something, Medito always surprises me with how much content it has and its amazing quality without asking you for anything.
Also, I've downloaded the nature sounds in-app and use them when I'm doing something I need to focus on. Nothing like reading a book with calming rain as white noise.
Ohhh... I've only ever used white noise to drown out my annoying brain noise when I'm trying to sleep, I hadn't thought of using it to focus when I'm awake!
I'm sorry to hijack the thread, but have you tried brown noise (more like car noise than rain)? A bunch of people swear by it for making brain go quiet.