2 very useful mind mapping tools that i have explored are
and Mindomo (www.mindomo.com).
FreeMind is an Open Source software and allows one to create mind maps and save them in various formats. A simple to use interface with all the basis formatting tools to create mind maps. The detailed documentation available at the website makes it easy to understand and use. FreeMind is created using Java and so requires JRE ( Java Runtime Environment) to be existing on the machine. JRE could be downloaded from SUN site (www.sun.com). The FreeMind download site also provides a link for downloading the JRE. When installing FreeMind, please ensure that JRE is installed prior to installing the FreeMind software. A very useful software to create mind maps and integrate it into blogs, wikis, etc. The latest version 0.9.0 has been released.
Mindomo is an excellent online mind map creation site. A nicely laid interface with lot many features enables one to create good, useful mind maps. It surely offers lot many features and options to make it a must try. The toolbar has sufficient tools to churn out beautiful mind maps. This online definitely scores over the offline one mentioned above. After creating, you may put your mind map in Public folder to share it with others and enable them to use it or else put it in Private folder.
Tried my hands at both to create some real basic mind maps as pasted below