One Column Themes
Revolution-X is a one column theme with three customizable widgetized sidebars at the bottom. The theme has a featured article section and built in transparency for linked images.
Two Column Themes
Dieanel is a simple two column widget-ready theme. The theme makes use of blue colors intelligently blending the theme nicely.
Loopy Rainbow is a two column widget-ready theme, the theme is simple and comes with a sidebar to the right side. As the name suggests the theme comes in 7 colors and you can choose from blue, black, red, purple, pink and rainbow colors.
Valid Blue is a two column widget-ready theme which makes use of darker shades of blue color. The theme is XHTML / CSS valid.
Three Column Themes
Pistachio is a three column widget-ready theme with unique icons. The them is Gravatar ready and also highlights post author comments. The theme is compatible with WordPress 2.3 and above.
Blue21 is a simple and clean three column widget-ready theme for WordPress. You can easily place a skyscraper banner in the middle column of the theme.