Starting to play with those. So just FYE, here is what I wrote yesterday:
// create the new document.xml package part
Uri documentUri = new Uri("/word/document.xml", UriKind.Relative);
PackagePart documentPart = package.CreatePart(documentUri, "application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml");
XNamespace r = "http://schemas.openxmlformats.org/officeDocument/2006/relationships";
XNamespace wp = "http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawing";
XNamespace w = "http://schemas.openxmlformats.org/wordprocessingml/2006/main";
XNamespace dm = "http://schemas.openxmlformats.org/drawingml/2006/main";
XNamespace dp = "http://schemas.openxmlformats.org/drawingml/2006/picture";
var firstParagraph = new XElement(w.GetName("p"),
new XElement(w.GetName("r"),
new XElement(w.GetName("t"), "A paragraph")));
var secondParagraph = new XElement(w.GetName("p"),
new XElement(w.GetName("r"),
new XElement(w.GetName("t"),
new XAttribute(XNamespace.Xml + "space", "preserve"),
"A ")),
new XElement(w.GetName("hyperlink"),
new XAttribute(r.GetName("id"), "rId2"),
new XElement(w.GetName("r"),
new XElement(w.GetName("rPr"),
new XElement(w.GetName("color"),
new XAttribute(w.GetName("val"), "0000FF"),
new XAttribute(w.GetName("themeColor"), "hyperlink")),
new XElement(w.GetName("u"),
new XAttribute(w.GetName("val"), "single"))),
new XElement(w.GetName("t"), "hyperlink"))));
var graphic = new XElement(dm.GetName("graphic"),
new XAttribute(XNamespace.Xmlns + "dm", dm.NamespaceName),
new XElement(dm.GetName("graphicData"),
new XAttribute("uri", dp.NamespaceName),
new XElement(dp.GetName("pic"),
new XAttribute(XNamespace.Xmlns + "dp", dp.NamespaceName),
new XElement(dp.GetName("nvPicPr"),
new XElement(dp.GetName("cNvPr"),
new XAttribute("id", 0),
new XAttribute("name", "openxmldeveloper.gif")),
new XElement(dp.GetName("cNvPicPr"))),
new XElement(dp.GetName("blipFill"),
new XElement(dm.GetName("blip"),
new XAttribute(r.GetName("embed"), "rId1")),
new XElement(dm.GetName("stretch"),
new XElement(dm.GetName("fillRect")))),
new XElement(dp.GetName("spPr"),
new XElement(dm.GetName("xfrm"),
new XElement(dm.GetName("off"),