One Column Themes
WP Silver is a one-column theme with three widget-ready sidebars in the footer. The theme makes use of CSS drop down menu and Social Bookmarking reloaded plugin.
Two Column Themes
Mystefied is a two widget-ready theme column theme. The theme is simple and has a extended header where you can add content such as latest posts, popular posts, etc.
Deserta is a fixed-width, widget-ready 2 column theme with a right hand sidebar. The comments are gravatar-enabled and will work whether you’re using WP2.5 or lower. There’s also separation of user comments from pingbacks/trackbacks.
Structure is a two column, widget-ready theme which includes built-in video and image features that easily allow you to customize your site. There are content blocks that you can place virtually anywhere on the page.
Dark Room is a dark 2 column theme suitable for personal and photo blogging.
ScrewDriver is a two column widget ready theme. The theme has lots of nuts in it. Overall a decent theme which you can download and use.