IdeasOnCanvas GmbH has MindNode – Delightful Mind Mapping (iTunes Link) for the iPhone, iPod Touch, iPad in the iTunes App Store for FREE (regularly $9.99) for a limited time.

MindNode makes mind mapping delightful. Mind maps are a visual representation of your ideas, starting with a central thought and growing from there. MindNode allows you to brainstorm, organize & share your thoughts in an intuitive way, so you can focus on the idea behind it. The clean interface lets you concentrate on generating and connecting thoughts, and an infinitely expanding canvas means that no matter how big or complicated your project gets, MindNode can keep up.