Ask HN: What app/system do you use for saving notes?

I'm making a note-keeping web application and am looking to do a bit of idea validation. I'd really appreciate if everyone that read this could answer any or all of these questions:

A) Do you have a system for saving information to reference later?

B) What is your currently preferred app/system/setup for doing so?

C) What is one thing that bothers you about your current system you wish was done differently?

I'd love if you could give an up-vote and maybe get this to the front-page for maximum exposure. Thanks!