CmapTools is a Free application created by Joe Novak and his people at University of West Florida at the IHMC. You can download it for free from their website
but you do have to register first (hmmm... looks like you don't have to anymore). Here are some IV's to help you get started with CmapTools. At the bottom of this page are further IV's.
These people actually create 2 complimentary pieces of software: CmapTools and CmapServer. The first one is run on your computer; the second one is run on an Internet server and you can access it with CmapTools. You make your concept maps with CmapTools and you can store them on your computer, or you can store them on line at one of the CmapServers. Needless to say, you have to have access privileges on the CmapServers to be able to create, store and organize your concept maps on line.
Following are some videos that will help you start to use CmapTools and get on line and organize your work on the Internet. More videos can be found on the Concept Mapping
Making and Saving a new Cmap File
Opening an existing Cmap file from the Internet
Making bubbles on a Cmap
Grouping Bubbles on a Cmap
How To Link bubbles and make arrow heads appear on a Cmap
How to make 2 kinds of links and make arrows
Finishing to Make your map (7 minutes)
This short video shows in detail how to link bubbles