Twenty Eleven Theme Extensions by Mike Walker is an easy-to-use plugin designed for use with the latest default WordPress theme, Twenty Eleven. It adds a set of customizable features for the theme, designed to add more flexibility to the theme’s design without having to modify the template files.
Add the widget sidebar to all pages, and single-post pages.
Optionally center the navigation links at the top of single-post pages with a sidebar.
Change the default height of the banner image in the header.
Adjust the alignment of sidebar widget titles.
Automatically turn sticky posts into single-line headlines to alert your readers of something important.
Add custom CSS styles for your site safely in a place that won’t be overwritten when you update WordPress or Twenty Eleven
Plugin homepage: http://moztools.com/wordpress/theme2011-plugin/
Download and info: http://wordpress.org/extend/plugins/twenty-eleven-theme-extensions/