Anahita is a free child theme for Genesis framework by Studiopress. It features a soft, pastel, feminine colour scheme.
Mixr is a child theme for Stargazer with a bold colour scheme and an all-new layout.
Relativity is a simple, one-column WordPress theme for personal blogs. It is also suitable for use a starting point for your customizations. Relativity supports custom headers, custom background, and various post formats.
Polymer is a child theme for Stargazer by Justin Tadlock. It is inspired by the Material design color palette by Google.
Center is a simple, one-column, blog child theme for Genesis. It provides a clean layout for a personal blog or website.