List of Free code CSS
An ASP.NET Ribbon that looks like Office Web Apps, Office 2010 and SharePoint 2010. Give Office 2010 look and feel to your web app, without having to hard code CSS.
CSS Friendly Control Adapters
The CSS Friendly Control Adapters kit (for ASP.Net 2.0) provides pre-built control adapters that you can easily use to generate CSS-friendly markup from some of the more commonly used ASP.NET controls.
RoundPanel Server Control
An asp.net server control that generates standard html layout for round panels. The source code demo has a few css available free to download.