I recently came across Mind maps.
I find them to be excellent for designing/architecting. Much better than a design document with bullet points and long descriptions.
If you think about it, take any problem, you usually end up first breaking down the high level concepts, then working your way down to the details of each in a hierarchical manner. Mind maps allow that naturally, and I have found them better than anything else to put thoughts on paper.
Below is a mind map showing the design of the ‘Open External Recording‘ dialog in Chronon.
Notice how easy it is to see each case and go all the way down to the minute implementation details of each. It is much more consice that a long design document and conveys the information much more clearly.