Exploratree (exploratree.org.uk): This is a great visual site with lots of templates for creating a mind map.
Mind42 (mind42.com): This is an easy-to-use collaborative mind-mapping site with many different templates.
MindMeister (mindmeister.com): This is a great mind-mapping site that allows you to embed them into a a blog or website.
MindMup (mindmup.com): Fir mind maps or brainstorms, this is an easy-to-use site.
Mindomo (mindomo.com): This is a brainstorming app that also allows users to flip their classrooms, collaborate, comment, and a whole lot more.
Popplet (popplet.com): This is an app that allows students to think and learn visually by creating mind-maps and brainstorming.
StoryboardThat (storyboardthat.com): This site features an educational portal that educators can use in a variety of ways to create timelines, storyboards, graphic organizers (t-charts, grids, etc.), and much more.
TotSplash (totsplash.com): This is a fun site for creating and organizing ideas into a mind map or brainstorm.
Webspiration (mywebspiration.com): This web-based program is popular for creating visual brainstorms that can quickly and easily be turned into an outline.
WiseMapping (wisemapping.com): This is a great site for creating brainstorms and visual mind maps.