I've been a member of Toastmasters for a couple of years. During that time, I've used a number of methods for preparing speeches, including notecards, fully developed and highly polished text, slide decks, and maps. I find the map to be the most effective method for quickly developing an organized speech and a set of notes that will fit on one piece of paper.
Here is an example of a map I developed for my latest speech.
Click on the map to open as a larger image in a separate window.
Depending on the intent of the speech, the map can also become a handout for audience members. A much simpler map around the same theme could also serve as outline for an hour long workshop, allowing audience participants to start thinking about developing their own learning plans.