From Webyog Softworks:
Visifire is a set of open source data visualization components - powered by Microsoft Silverlight. With Visifire you can create and embed visually stunning animated Silverlight Charts within minutes. Visifire is easy to use and independent of the server side technology. It can be used with ASP, ASP.Net, PHP, JSP, ColdFusion, Ruby on Rails or just simple HTML.