Thinklinkr is a site that allows you to create collaborative online outlines. It's a freemium site, meaning that there is a free version and there are fee-based versions that add more functionality. The free version offers unlimited outlines, but they are all public. You can not make any private. For most educational uses, this is probably ok.
It is very easy and simple to use. Use it to create outlines for projects, run meetings, do brainstorming, organize your thoughts and much more. Students, teachers, and administrators can all use it for different activities. Students can work on a project or paper together. Staff can work on meetings together. It is a very useful site.