Mind maps are fundamentally very simple. You can create one on the back of a napkin in mere seconds, so it follows that there should be an equally effortless way to do it online. And there is: MindMup, a free and lightweight service lets you throw together simple mindmaps without having to download anything, open an account, or do anything else. It's Web-based, too, so it works across Windows, Mac OS X, and Linux. See all: PC Advisor software downloads.
When you go to MindMup.com, you first see a default map explaining how the service works. It goes over keyboard and mouse use, and includes notes on how open and frictionless the service is. And for once, it's no hyperbole: MindMup requires no registration to work, not even when you save your mind map. And if you're afraid of saving your work to the service, you can easily connect it with your Google Drive, or even save to the local browser storage using HTML5.
Making your MindMup
MindMup supports undo and redo operations, but doesn't have a fancy timeline interface like the one MindMeister uses. Its interface consists of a top menu bar and a floating toolbar, both of which can be collapsed. In its barest form, only the mind map is visible. To access the menu once you've collapsed it, simply hover your mouse at the top of the screen, and the menu will become visible. Once the time comes to share your work, you can export it to .png or FreeMind .mm formats, or you can simply share the link to MindMup. Anyone clicking on the link will see your mind maps and be able to make changes, but the changes will be saved in another copy. They can share that new copy with you, of course, but that's no substitute for real-time collaboration.
MindMup is super-simple, lightweight, and generally a joy to use. The next time I need to jot down a quick mind map to explain a concept or make sure I cover all bases at a meeting, I may well use it.