We use MindManager for large scale projects to create a "40,000 foot" view to easily see what's going on. From there we can navigate to a subproject to discuss or get a visual of what needs to happen. They say a picture is worth 1,000 words, this is what we use to create our picture. Bringing a large detailed gantt chart just gets blank stares and little understanding. Bringing a visual presentation from MindManger to a meeting allows everyone to easily see what's going on or verify that everything is accounted for.
We also use it on a smaller scale to help with brainstorming during meetings. It's so much easier and faster to use it than trying to write on a board. Adding priority and catagorizing on the fly with a nice looking clean interface is great.