Ask HN: How do you capture/keep your ideas?

I'm thinking of tackling these two problems:

(1) Ideas happen anywhere, anytime (running, in the shower, driving, etc). How to capture these ideas before they vanish?

(2) I use notebooks, but once I write down an idea chances are that I will never see it again. I have a box full of notebooks collecting dust.

I want to know how do you capture/keep your ideas (notebook, an app, eidetic memory, napkins, mails to yourself), what do you like/dislike about your current way, and what have you tried and didn't work/stick.