if you use wordpress you will probably already know this, but you can find literally thousands of free, excellent wordpress themes at http://themes.wordpress.net/

the themes are free and there's a search function to filter the temes

the search doesn't work so well, anyway...you just have to browse them and you'll find the one you need

if you know any other source for FREE wordpress themes post it here, we could build a nice list of sites that have free wp themes

http://www.freewordpressthemes.com/
http://www.wpdesigner.com/
http://www.wpthemespot.com/
http://www.wpthemespot.com/

Thats alot.. but I have more.. I am a WP Fanatic

Thanks Zalaki for providing all the links to the wordpress themes!

I found a couple more wordpress themes.

http://www.ndesign-studio.com/resources/wp-themes/

And yet a few more wordpress themes are available at these websites:
http://wordpresstheme.info/ (go along sidebar to see the different themes, currently there are 4)
http://www.blog-star.net/designer_theme/
http://www.blog-star.net/urban_theme/

Good resources, thanks.

Here is a blog post I made on some of my favorite themes - contains links to several free WP Themes sites.