Blue Grace is a simple three column WordPress theme with a rotating header image
Two column WordPress theme which really lets your blog stand out from the crowd. Make your blog unique by changing the main blog color (pink, yellow, green), background pattern (available over 20 background variations), banner etc through an options page. In addition you have the ability to choose the color of sidebar blocks (violet, yellow, green).
Two column, white and grey, gravatar theme with ad ready stops with psd files included
Hello Red is a 2 column red, white, and black, widget ready WordPress theme.
Three column, widget ready, fast loading, search engine optimized theme
On the subject of themes, Matt has a tutorial Separating Pings from Comments in WordPress 2.7.