controles prontos e opensource em Silverlight!
mmmmuito legal: gráficos e diagramas gratuitos e opensource em Silverlight... veja o vídeo acima e depois confira essas features no site deles:
Silverlight & WPF Charts
Visually Stunning Animated Charts
Single API for both Silverlight & WPF
Embed into Desktop or Web Applications
Tiny footprint (204 KB)
Dual License - Open Source & Commercial