Azul is a really clean and modern free WordPress theme that comes with many premium-like features and a very clean-coded back-end. Ideal for all sorts of blogs.
Lempong is a unique WordPress theme with a coin slider.
tweaker3 is a theme specifically built for those who love tweaking their own themes. Open, clean and quick-loading design with a wide sidebar on the right.
zeePersonal is a dark 2 column theme with great features, like Custom Logo, Custom Font Color via Colorpicker, Content Slider, and more.