Mac: Dumping out all of your ideas into a computer isn't easy. The formatting is often too rigid to just throw down a load of words and make connections later. Scapple is a piece of software currently in beta that works something like a freeform text editor so you can get rid of ideas quickly.
Unlike mind mapping software or a traditional text editor, Scapple doesn't have any set format. Simply double-click anywhere on the pad and start typing. You can then attach new ideas with arrows, lines, or just leave them on their own. It's a close analogue for a piece of paper you're just quickly jotting down ideas on. Scapple's current version is a beta that will expire at the end of the year, but it's worth checking out if you prefer to keep your notes freeform and messy.