Viewport3D.com
Daniel Lehenbauer's Home Page
Books:
WPF Unleashed
Blogs:
WPF 3D Team Blog
(old stuff
here
)
Code:
3D Tools for WPF
Samples from WPF Unleashed
Tools:
Designers and Exporters for WPF
(includes several options for 3D)
Videos:
Interactive 2D Controls on WPF 3D Surfaces
3D Intergration in WPF
Demo of Avalon 3D
(on historical interest only)