MindMup - Free Mind Map web site
MindMup is a free mind mapping site that has some nice features. It's easy to use, you can save your maps to Google Drive or Dropbox, you can use Rich Text, import images and export your files and even embed your map in a site. You can collaborate with multiple users on the same map, which is great for classroom and group projects.
There is also a Chrome extension available.
More MindMapping Apps and Resources