Website templates lists, I'll try to update this page as and when I find new sources.

Updated
Yet more XHTML and CSS Templates

http://www.1stwebdesigner.com/resources/101-high-quality-css-and-xhtml-free-templates-and-layouts-part-1-2/



High Quality Templates

http://www.hongkiat.com/blog/38-free-elegant-xhtmlcss-website-templates/

http://www.mantisatemplates.com/free-web-templates.php#brown

http://www.smashingmagazine.com/2008/12/01/100-free-high-quality-xhtmlcss-templates/


E-commerce Templates

http://www.smashingmagazine.com/2009/01/25/35-free-high-quality-e-commerce-templates/

CSS Based Template list

http://www.smashingmagazine.com/2007/02/14/free-design-templates/

Open Source:

http://www.oswd.org/

http://www.opendesigns.org/

Various:

andreasviklund.com

All templates are made with valid XHTML (strict) and CSS, and they are supposed to be small, easy to work with and of high code quality.

Styleshout

Styleshout templates are all css based, updated regularly and can be used under the Creative Commons Attribution 2.5 License, there are some nice templates in there.

Arcsin

Another batch of nice css website templates which again come under the CCA license. There are also wordpress themes to smarten up your blogs.

Clip Art:

http://www.openclipart.org/