My favorite software for outlining is Inspiration. You'll find all the information about the product at their website (Inspiration.com). Academic Support professionals at law schools across the country recommend it to their students.
One of the best features is this: you can draw a flowchart OR type your topics and information into a traditional outline format -- then the software switches from one to another. This accommodates different learning styles, and is a very easy way to develop flowcharts of your own.
Write me if you have any questions about outlining or flowcharting. I'll be happy to help.