Mind42 (Online Mind Mapping Software)
Great for Teachers and students, a browser based online mind mapping application. Just open the browser and launch the application when needed.
This is a very user-friendly online web application to manage your mind-maps. It can also be used as a site mapping tool for a website.
However you decide to use it, you will like it’s great interface and features.
Once logged in, you immediately start putting together your mindmap with colours, multiple nodes - all the usual features of mind mapping software, and then some.
Features that provide that extra bit of functionality include:

• You can export your mind42 mindmap directly to Mindmanager, or even just RTF (Rich Text Format).
• Publishing features include making it ‘go live’ for the rest of the world to see.
• It allows you to publish your mindmap directly to your blog platform.
• You can add icons for each node, add attachments, create links, choose colours.

Creately

Draw and design almost anything with Creately. Create and collaborate on diagrams, charts, sitemaps etc... Drag and drop interface. Try it.

Diagrammr

Create and share diagrams by writing sentences. Another Web 2.0 tool worth trying. Login and save your diagrams from your Google account.

Xmind

XMind is a mind mapping tool with a difference. It is easy to use, open source software that allows the user to create visually appealing mind maps. There are several options available to easily customise your mind maps, including inserting your own images. These can be uploaded and embedded online at XMind.Net.