Topher

Provides a user interface under the Reading Settings page for choosing what post element to orderby. Also allows the site owner to chose ASCending or DESCending.
NOTE: Does not allow for arbitrary ordering via drag and drop. This is a simple setting.
<h3>Usage</h3>
Once it’s installed, go to Settings -> Reading section, scroll to the bottom, and choose an orderby and order option.

Default Post Sort

I'm glad I came across this plugin. It does exactly what the title says and nothing more which is what I want in a plugin. 

Simple and straightforward. Great plugin.

Provides a user interface for setting a default post order.

Chip Bennett

This plugin will allow you to customize the number of posts, orderby, and order parameters for all index page contexts, including the blog posts index, search index, and all archive indexes (category, tag, taxonomy, author, date, archive). Orderby settings support all values relevant to archive index pages, including none, ID, author, title, name, date, modified, rand, and comment_count. Order settings support ASC and DESC.
Note: Plugin settings can be configured via Dashboard -> Settings -> Reading.

cbnet Different Posts Per Page

Customize the number of posts, orderby, and order parameters for all index pages (blog/home, search, category, tag, taxonomy, author, date, and archiv …

Default Post Sort vs cbnet Different Posts Per Page