A very impressive datagrid and date-picker for WPF available for free (in exchange for your name & email). Has a *really* slick "Card" view, as well as fully hierarchical standard grids and more. With all the usual in-place cell editors, XCEED's WPF DataGrid is fully styleable and templateable.
Part of a book by Charles Petzold on programming Windows apps with WPF -- includes a link to all the code samples -- which are really great as a learning tool even if you don't have the book.
Wherein the author presents a recipe for job security: tie development so closely to an understanding of corporate workflows that it's irrevocably knit into the fabric of the company and colocation with users ... It's important to note, however, that the sort of development he's talking about is strictly the light-weight "in house" variety -- not the development of externally facing applications for sale.
WPF has two ways to create documents: XAML Flow documents paginate dynamically and flow into multiple columns at different zoom levels, etc. XPS documents are print ready documents on a fixed page size. Converting Flow documents to XPS isn't hard, even when you want to take advantage of the extra features like custom pagination, page size, margins, and headers or footers.
ExtensionMethod.NET is a database of C# 3.0, F# and Visual Basic 2008 extension methods. It contains many user-rated extension methods that will expand your code library immediately.