MindMaple Lite is a free download for Windows users who want to create mind maps on their desktops. Like any good mind mapping tool Mind maps created with MindMaple Lite can include images, links, and text. One of the handy features of MindMaple is the ability to draw loose elements into a group. In other words, you don't have to construct elements in a connected sequence. You can move elements of your mind map into groups after you've put them on the canvas. Completed mind maps can be exported to Microsoft Office.
Asana is a task management tool for groups. Asana allows you to create multiple projects and lists of assignments for completing each project. Within each project you can assign tasks to the members of your group. Groups can have up to 30 members in the free version of Asana. Asana provides feeds for your projects so that members can subscribe and receive updates about new assignments and progress toward the completion of projects.
Asana has a mobile website that you can use on your iPad or Android tablet.
There is a free version and a paid version of Inkflow. The free version allows you to use black ink only and your books are limited to twenty pages. But you can have as many books as you want in the free version. The paid version gives you more drawing tools and colors as well as more pages per book.
Oh, and it is FREE!