“WP-dTree” created by Christopher Hwang a good plugin for people want to have a fancy look on their archive part of the blog, it is not completely widgetized but it is very good plugin for people who know PHP and JavaScript.
And if the other Chirstopher wordpress plugin “WP-Scriptaculous” plugin is active the collapsing of archive can be even fancier, four different type of actions allows people to have a good visualization on their blog.
Both of the plugins can be downloaded here
