Thematic is a free, open-source, highly extensible, search-engine optimized WordPress Theme Framework featuring 13 widget-ready areas, grid-based layout samples, styling for popular plugins, and a whole community behind it. It’s perfect for beginner bloggers and WordPress development professionals. The coding, functionality and support of Thematic rivals the best in “premium” themes. With one, important, difference—Thematic is completely free and open source. If you haven’t started using Thematic for your blog yet, keep reading and find out why you’ll want to. 
Thematic Features:
- Continually advancing Search Engine optimization
- A host of professional, ready made Child Themes that extend and update Thematic. Check out Acamas and Travailler and all the other Thematic Child Themes in the sidebar.
- A sample Child Theme is included in the download to rapidly get you up to speed on modifying your WordPress theme the smart way.
- An easy to follow Guide to Customization full of code snippets you can just cut and paste into your Child Theme.
- Ready for Subscribe to Comments, WP-PageNavi and Comment License
- Fully widget-ized with widget areas above and below the content—and even in-between
- Easy to implement, bullet-proof, grid-based, sample layouts based on the 960 Grid System that cover all the popular blog styles: 2 columns, left and right, and a 3 column stylesheet with both sidebars on the right
- CSS Reset and Typography based on Blueprint and Tripoli
- Dynamic body, post and comment classes, making it perfect for customization, and auto-enabling popular features like “aside” posts and post-author styling.
- Editable footer text; take out the theme credits from a theme options page without harming the theme.
- Options for Multi-Author blogs
- and more coming …
You can see this best SEO wordpress theme( a killer SEO theme– Diythemes Thesis WordPress Theme)
