Just downloaded freemind today to help with plotting a novel (it was suggested by a how-to-plot-your-novel blog post).  I draw mind-maps all the time, but a piece of paper is so limited.  Freemind feels really natural.  I have tried other novel outlining software, but the great thing about Freemind is that I can create a node for stuff that I don't know what to do with, and easily move the items into the correct nodes once I figure out what's going on.  I can easily transition from an unstructured brainstorm to an ordered list.  I can look at my ideas spatially and move them around without the annoyance of index cards, post-its, etc.  Really looking forward to using this heavily.