Member of network of sites that sell all kind of templates. At the moment of review they are offering unlimited membership for $49.99 (28 categories) which to me appears to be very good deal.
Another simple blog with dozens of free Word Press themes. It does not have thumbs for all themes so you have to visit demo to see design of the theme.
State of the art Word Press themes here although little bit pricey. Still worth visiting to see how WP can be used to create fancy portals and complex web sites.
Several nice free themes here. Not categorized. Have not been around for long time, so it's not so rich in content like other free sites. Demo preview available.
