The past months I've been working on a project called AngleSharp in my spare-time - now it's time to release it. The library is actually far from being finished, but it is good enough to do some productive work with it.
The main principle behind the library is that is a .NET DOM generator. Right now it parses HTML5 and CSS4. While the HTML5 DOM is ~80% implemented (the objects are all available, but some methods or properties are not implemented or not connected), the CSS4 DOM is about 30% implemented (a big part is missing due to treating all declarations as general CSSProperty objects with generic values instead of specialized ones).
Nevertheless I am able to run queries against the generated DOM and get information of the document itself. The parser uses the official W3C specification (HTML 5.1).
In the future the complete DOM will be implemented. Additionally a lot more possibilities will be integrated, which will allow AngleSharp to do resource management and much more. A valid Xml parser will be integrated as well, which will then be used for XHTML, SVG and MathML documents.