I use the following tools for WPF development:
- Snoop - This tool simplifies debugging of WPF apps at runtime.
- Mole - Awesome visualizer for Visual Studio. Highly recommended for not just WPF work (although it was built for WPF).
- Kaxaml - Great little tool to “play” with XAML. Full intellisense. I use it to see how XAML will be rendered.
- Expression Blend - Mainly for copying control templates, but also some styling work.