short article Mike Gunderloy talks about light and easy tools for requirements gathering and brainstorming. In particular, he mentions MindManager product as a useful tool. I could not agree more. Most of the brainstorming, agenda-creating, and multi-task tracking I have to do I process through this tool. Whenever I have to think of a new module for my product - I first turn to Mindmap to sketch out the contours, then onto Jude UML to work out use cases and basic model outlines.
I would not mind if MindManager had a UML extension for creating use cases and some simple class, sequence, and activity diagrams. While that is not what the product is about, it would make it rather suitable for purposes I use it for -- quick software module prototyping and brainstorming.