Hybrid Core

Hybrid Core is a WordPress theme development framework for creating solid parent themes. It allows theme developers to forget about all the complex functionality and dive straight into coding their theme’s HTML, CSS, and JavaScript.

This framework’s code is completely free and open source. You can use it for creating publicly-downloadable themes, client work, or even a commercial theme business.

Builder

iThemes Builder is a powerful, flexible, easy-to-use WordPress theme designed to allow you to quickly build websites and blogs with WordPress. With Builder’sinnovative Layout Engine, you can build almost any layout you’d like within minutes. Then bling out your site with graphics and styling.

Iridium

RocketTheme’s Iridium is a WordPress 3.0 theme that has six style variations and a ton of widgets out of the box. It’s very graphic and great for sites that need more than a subtle look and feel.

3.0 Basics

This WordPress 3.0 based theme is a free theme that is the perfect starting point for theme developers making a new theme. It has many common features used by plugins built-in as well as a pre-made custom post type that allows you to build a site where you or your users can post links to your favorite sites, which will automatically generate a screenshot image of the website to be displayed on the page.

Skybox

Beautiful full screen theme. Perfect for portfolio, photography and boutique sites.

Headway

Headway is a great framework that allows non-designers the chance to make an attractive looking website very easily. With a built-in Visual Editor, and a friendly and very helpful support community, Headway is shaping up to be a very tough competitor in the Framework world. Headway also has top notch search engine optimization, custom css/php options for developers, and a configuration panel that makes creating a website a snap.

Thematic

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.

Hybrid

Hybrid is a free, open-source theme framework.

WPStartbox

StartBox is a great theme framework for WordPress. It comes with an incredibly easy-to-use, modular settings page. For users, this means a quick and painless setup for your website, for theme authors this means an incredible new level of control for your themes.

eZine

Clean vibrant dark theme with a full screen background image