I'd say Arthemia, Revolution Church when it was free come off the top of my mind as some very good free Wordpress themes.
I'd say that ThemeShaper's Thematic Wordpress Framework is awesome if one knows how to customize WP themes. The theme doesn't look very attractive in its original form, but you can make it into a beautiful one by customizing it.
There is also a small Guide for Thematic Customization.
Plus, since its open source, you aren't required to keep the footer link. You can remove it if you wish. Isn't that great?
I create my own themes =D just like the personal touch it gives.
Owner and writer of: http://www.gayadesign.com
Editor of: http://www.fuelyourcoding.com
FUELEY IS DEAD!
All of the Revolution 2 themes are nice. They were free a few months back but now they charge. I have them all if anyone would be interested I can upload.