MindMup is a free mind mapping tool that can be used online.
MindMup works like most mind mapping tools in that you can
create a central idea and add child and sibling nodes all over a
blank canvas. MindMup nodes can contain text and links.
When you’re ready to save your MindMup mind map you can
save it to Google Drive, save it to your desktop, or publish it online.
There is now also an offline version of this!!