I have been testing out a new product from Altsoft, called Altsoft Xml2PDF. I like the ease with which you can start from a WordML document and generate the PDF out of it. They also have a .NET API so you can do the generation of the PDF at the server-side in for example an ASP.NET application.

Altsoft Xml2PDF is a .NET based formatting engine for converting XSL-FO, SVG and XHTML files to PDF. It takes XSL-FO, SVG, XHTML or XML+XSLT files as an input and supports compression, font embedding/subsetting, security, interactivity and many other features in PDF generation.

You can download an evaluation version from their site.