Simple Diagrams is a site I just found out about from Free Technology 4 Teachers. This is a site that offers a tool (adobe air install) for creating simple easy to use diagrams. This is ideal for brainstorming or mind mapping and can be a real asset for educators. There are lots of nice features such as adding photos, drag-n-drop interface, and ability to change background. Keep in mind there is a paid and free version.
I recommend checking out Simple Diagrams by clicking here!!
Click here for my top 10 on brainstorming.