Curio is a terrific application for the Mac. It's a general purpose planning, scheduling, diagramming, note-taking and mind mapping tool. Version 9 is out now and it's a $50 upgrade for owners of the previous version. This is one of those tools I return to again and again.
The new version has been redesigned and already is geared toward Yosemite. I like the new artboard1 for project pages. Throw lots of stuff on one and it acts as an idea space inside an idea space.
But by far, the best new feature is support for iThoughts files. Just drop them onto a Curio idea space and it offers to convert it to a mindmap inside the the project. It even supports the iThoughts task management properties if that's your thing.