Does it existe a "generator" for asp.NET that generate flash rich application?
The same job as ColdFusion or Flex does, but using .NET.
We could create forms, charts, tab, grid applications...
Macromedia as a release of that kind of control?

No, but you may want to look into this
http://www.xamlon.com/software/xamlonpro/flash/
I haven't ever tried it out but the demo apps are pretty cool... I think you
might need to use C# or XAML but it looks like a cool app.