Display post titles in a listbox

We are looking to display all post titles within a category in a scrollable listbox or drop down. Ideally we would like to provide the user a list of the categories, once a category is selected all posts within that category would be displayed in the listbox (dropdown). When clicking on a post title in the list that post would be retrieved.

Is a script for this available or is there a plugin that does this?

We looked at the plugin by Dagon Design but that seems to be limited to a single category which is preset. We would like to avoid populating a list before a category is selected by the user.