Any storyboard program you can suggest for writing out map ideas?

[Havok]

Before I actually make a WAD I roughly write down the major things that I want to happen in the map such as the enemy encounters and puzzles, etc. But each thing can be quite long so it makes it hard to read the document at a glance and find everything. Is there a storyboard program or other program you can suggest? I'm thinking maybe I can write a short summary for each thing and then when I click on that it will open the full story for that particular thing in another tab or something.

[Majin]

pureref is good at putting down images and textboxes in a canvas