Fluid2 is a 3 column wordpress widget friendly theme with a fluid layout based on a template by Dave.
Nature is a two column theme with a green header.
TheSpeedBlog is a fun two column WordPress theme with a widget enabled right-hand sidebar. Great for a motor racing fan of any kind.
Adsense theme is a widget ready theme filled with Adsense ads.
Salt and Pepper is a three column, fixed width, widget ready theme by Headsetoptions.
geepressed is a simple, green, two column Theme for WordPress 2.0/2.1.
Space Future is a search engine optimized two column theme.
Blueline is a 3 column widget ready theme by GPS Gazette with one sidebar on the right and one to the left of the content area that uses a soft color scheme and very few images.