30Boxes Online Social Calendar

Brainwaves Center offers free a fun and informative way to exercises your mind with a variety of interactive puzzles.

iOutliner is a free online application that allows you to manage your tasks, ideas, and projects in structured lists.

mind42 brings you free online collaborative mindmapping.

According to the site You can keep track of all your ideas, whether alone, with colleagues and friends or working together with the whole world.

The application is browser based online mind mapping application. With mind42.com installing mindmapping tools is no longer needed- for a hassle-free mindmapping experience. Just open the browser and launch the application when needed.