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.

afiskon

A widget that displays blog archive in two columns.
See the <a href="http://eax.me/two-columns-archive-plugin/" rel="nofollow ugc">Two Columns Archive homepage</a> for further information.

Two Columns Archive

A widget that displays blog archive in two columns.

Accordion Archive Widget vs Two Columns Archive