Hartee is a nice and clean looking blog theme, similar to the style made popular by Tumblr. It is responsive and built with the Skeleton framework so if you need to extend on it, it is easy to do. It comes with five different color combinations so your blog can stand out, or customize to your hearts content. It also comes with CSSIgniters Theme Panel which makes setting up themes quick and easy.
CSSIgniter is one of the best theme providers we highlight here at RWPT. They offer a number of quality themes, some responsive, some not. They do have some generic templates but also make templates for specific needs, which means they end up being more useful for their intended audience.