Expression Web Beta 1
I just blog'd about the CSS Control Adapter Toolkit here. If you are a web designer who has tried to use Visual Studio and found it lacking as a tool for CSS dev, then you will definitely want to check out Expression Web. Expression Web has a great CSS design time experience. There are quite a few videos in the Tours & Demos and Features section of the site. You can download Beta 1 of Expression Web here.
UPDATE: I pressed publish too soon! I forgot to mention that Expression Web allows designers to "take full advantage of the power of ASP.NET 2.0 with integrated support for server and user controls, and no code data binding." Finally, designers can build out the look and feel of the UI and developers can just load up the designers work in Visual Studio 2005 and code away!