We (Headspring Systems) are a client of PSD2HTML. We have a designer, but we have found it more cost-effective to have PSD2HTML take our initial UI designs and create XHtml and CSS out of them. From there, we will add these screens to the custom web application we are building.
PSD2HTML has several examples showing how a design is converted into XHtml and CSS. You can examine all the code on their examples page. It’s interesting to see the techniques used by a company whose core competency is XHtml and CSS.