I found four WordPress theme frameworks which worth to try out.
Hybrid is a WordPress theme framework designed with content in mind. There is no other theme that will display your content in a meaningful way like this one does. It’s all about getting your information out there to the world. Without all the fuss. That’s what Hybrid does.
This is more than just a WordPress theme: Thematic is a highly extensible, search-engine optimized WordPress Theme Framework featuring 13 widget-ready areas, grid-based layout samples, styling for popular plugins and more. The coding, functionality and support rivals the best in “premium” themes. With one, important, difference—Thematic is completely free and open source.
- WP Framework
WP Framework is a “blank” WordPress theme that empowers you to create awesome WordPress Themes in little to no time!
The Sandbox is a powerful tool available for WordPress theme designers and developers. The Sandbox can be easily designed just with CSS, so beginners will feel comfortable not bothering with PHP.
Experienced developers and designers can accomplish almost anything with minimal work, thanks to the rich, semantic markup and profusion of classes dynamically generated by the Sandbox.