Ashley

Expanding Archives adds a widget that shows your old posts in an expandable/collapsible format. Each post is categorized under its year and month, so you can expand all the posts in a given month and year.
This plugin comes with very minimal CSS styling so you can easily customize it to match your design.
JavaScript is required. No IE support.

Expanding Archives

This plugin adds a new widget where you can view your old posts by expanding certain years and months.

scribu

Smart Archives Reloaded allows you to display a list of posts grouped by year and month. It also provides several interesting navigation elements.
Format list:
<ul>
<li>list = a list of posts grouped by month</li>
<li>block = a compact block of links to year and date archive pages</li>
<li>menu = a two-level menu with links to year and date archive pages</li>
<li>both = block + list (<a href="http://scribu.net/archive" rel="nofollow ugc">example</a>)</li>
<li>fancy = menu + list + JavaScript (<a href="http://www.conceptfusion.co.nz/archive" rel="nofollow ugc">example</a>)</li>
</ul>
No support
I do not offer support for this plugin, either free or paid.
Credits:
<ul>
<li><a href="http://justinblanton.com" rel="nofollow ugc">Justin Blanton</a>, for the original <a href="http://justinblanton.com/projects/smartarchives/" rel="nofollow ugc">Smart Archives</a> plugin</li>
<li><a href="http://www.conceptfusion.co.nz/" rel="nofollow ugc">Simon Pritchard</a>, for the fancy format</li>
</ul>
Links: <a href="http://scribu.net/wordpress/smart-archives-reloaded" rel="nofollow ugc">Plugin News</a> | <a href="http://scribu.net" rel="nofollow ugc">Author’s Site</a>

Smart Archives Reloaded

Easily display posts grouped by year and month, in one or more elegant formats

Expanding Archives vs Smart Archives Reloaded