Single category drop-down advice?

Hi there,

I am trying to do emulate the dropdown menu option in the upper right hand corner in a WordPress site as seen here http://www.markdanner.com/writing/ using categories.

So there will be two separate parent category and a large number of child categories for each viewable through a dropdown menu. I want to be able to insert the code into the header or use a widget in the sidebar (if anyone can recommend one). I’ve done a lot of looking for a widget and don’t see one.

So the parent categories and child categories are as below. When you click on the parent category you get a full dropdown list of all the child categories. I see that the default widget allows you to get a dropdown list of ALL the parent and child categories, but I need to be able to separate the drop down list/option out by parent category.

Subject
-art
-dance
-ballet

Publication
-NYtimes
-Washington post
-Art daily

Thanks for any help!

Leah