DrawingBoard2 - A .Net GDI+ drawing component

The second project in our Diagraming week is one that I've wanted to highlight for a while. Imagine you need a diagramming, or drawing board, component in your app, kind of like a mini-Visio. Yet you also want to extend it, add to it (i.e. you want the source). You want something that is vector based, where you can diagram programmatically or your users can interactively and the diagrams can be serialized as binary or XML.