I've used FreeMind on and off for years, occasionally flirting with FreePlane and, most recently, XMind. The one thing that XMind has that I really like that FreeMind doesn't is multiple sheets within a single document, just like an Excel spreadsheet document can contain multiple sheets, with tabs along the bottom of the window. I find it extremely useful to have a single document for a project with multiple mind maps in it. I can have multiple projects open, and switch between them easily using...