I've been using this software for over 5 years now. Even though it's not entirely considered a mindmap software, it's completely free, simple to use, and can handle the task with hundreds of icons and options.

Being able to create visual representations of processes

The thing I like the best about it is that it can handle all the graphing I do for work from simple flow diagrams to complex relationship diagrams. Object placement and editing is very easy and uses standard left, center, right, top, bottom alignment. Can add custom objects. Can print as poster (multi-page mosaic). Useful icon-based controls. Lines, user controllable curves (I really like these)... and a lot of other stuff I haven't even gotten to using. (Oh, and it's free!)