WP Weaver

Twenty Ten Weaver allows you to tweak almost everything. You can change colors, fonts, sidebar columns, header size, and more. This theme also includes several new theme looks for an easy start. Just for example, this site is running on WordPress 3 and uses the “WP Weaver” sub-theme as its own theme.

Advantage Media Group

Advantage Media Group is a book/magazine publisher and interactive development house. Their site design is a custom child-theme of TwentyTen and they’re using custom post types across the site.