I want only the Parent Categories to show up at first

I am just transfering a site over to this software, and would like to categorize the posts by Author and Subject, as well as having a few main theme categories. Is there any way to have, for example:

1) About Us
2) Author
3) Subject

in the side bar, instead of a list of potentialy hundreds of names and subjects all mixed together.

When someone clicked on Author or Subject the menu would then need to expand in some way.

Thanks — Owen