blend modes and the potential of WPF (feature request)
Not just because of the ability to use it for non-destructive effects. Mainly I think this is a crucial feature because designers are used to it. Every compositing and imaging tool relies on this feature. It would solve one or the other problem, ease the work of the designer and it would be fun to use. Think of a the possibilites and cool effects you would suddenly be able do easily.
Xaml/WPF can also be thought of as a full fledged compositing/imaging ( multimedia authoring) toolset kind of like Adobe AfterEffects, Illustrator, Photoshop - just in the flavor of a programming interface.
If I remember right we have seen a XAML exporter for Adobe AfterEffects shown off at PDC 2003. The fact that a xaml exporter for an application like AfterEffects is possible and actually a practical idea is the best proof of the big potential of WPF. Who knows, some day we might see TV stations use the WPF runtime for the realtime composition of their broadcasted content.
AFAIK blend modes is the only major concept in that area that is missing in WPF to get on par.