Thoughtboxes is a free site that allows you to get organized using boxes that act like sticky notes. You can create categories and then create "thoughtboxes" in each category. You can use the boxes for to-do lists, notes, lists, links, and more.
It is very easy to use and very versatile. Create a main topic or "train of thought" and then create boxes of your thoughts on that topic. You can see all of your lists on one screen. The format makes it easy to brainstorm and organize ideas. You can even share and collaborate with others.
The site has examples and help section to help you get started.
This would be a great tool for educators to use while planning lesson activities or keeping track of ideas and resources. Students could use it for homework lists, getting organized, and as a type of mind map when getting their thoughts organized for a project or paper. The sharing and collaboration feature allows teachers to work on ideas with other educators and even hold virtual meetings. Students can work on projects together from home. I see this as a very useful tool for education.
The free version allows 3 trains of thought (the main topic) and you can share with others. Unlimited trains of thought are only $15 per year.
Here's and example: