I just discovered this theme new theme at the WordPress repository, it's named Gray Wolf.
I believe that it's a great addition to the themes that we already have.
You can see the live demo here: http://themes.wordpress.net/testrun/?wptheme=1522
It has a very neutral, classy look that would suit a lof of blogs.
Besides that it supports widgets, gravatar. Upon that it is xhtml + css valid.
More info here: