pathartl

Accordion Archive Widget is exactly what the name implies. It recreates the stock archive widget, but this time around the widget is laid out as an accordion. It gives you the years of the archive, and then when the year is clicked it expands to show the months.
Development can be tracked at http://github.com/pathartl/accordion-archive-widget

Accordion Archive Widget

An archive widget that reconstructs the stock widget into an accordion by year with month children.

Benyam.in

With WPArchivesTree you can display a widget which list all articles in your website on a treeview. 
Articles are group by month and year and you can choose if you want to display the first month articles or not.

WPArchivesTree

Put a widget treeview to list all articles in your website

Accordion Archive Widget vs WPArchivesTree