I do find audio routing and effects in Vista very inadequate. It would be nice to be able to plug in a mixer for example, instead of having to rely on manufacturer-specific methods where they exist. Or more simply, to be able to use directx or vst effects, for example to correct frequency response at a particular input or output.
You can do all this a complex way using Bidule and asio4all.
Bidule: http://www.plogue.com/?page_id=56