XMind Pro claims to be the most popular mind-mapping tool on the planet. You can use it to work through an individual brainstorming session and it will record and collect inspirations as you go. It can display as a mind-map or in a Gantt chart, and it works well with Office and can export in a number of ways to facilitate making reports. Version 8 has a refreshed look and a new slide-based presentation mode and the popular Walk Through presentation mode is still available.
XMind is an open source project, which means it's free to download and free to use forever as a version that allows you to make all kinds of diagrams. The price shown here is for Xmind Pro which includes all of the following features: