ElegantBlue is a 2/3-column, widget-ready theme with support for tags and separated comments and trackbacks.
Integral is a 2-column with light green, blue, and white colors.
Jello Walla Mello is a news/magazine style theme with sub-page design for individual entries and separated comments and trackbacks.
Linear is a simple, gridded theme for WordPress. Also check out Overshadowed and Verso by the same designer.
Rihanna is a 3-column theme with lightweight design and built-in Flickr support.
sIMPress is a 3-column theme that is compatible with WordPress 2.3 and supports ads and SEO.
Tumblelog is another tumble-style theme that hugs the left side of the screen.
Widejournal is a 3-column theme built on Sandbox with support for tags.
Wine Cellar is a 3-column, widget-ready theme with support for tags.