You're 100% correct about the state of documentation. I think we need to figure out a nice, centralized place to put up quality Haskell documentation, and actually work at it.
My feeling is that we lack mostly short, tutorial-style introductions, that just get you started with a topic/library. Ideally we'd have a way to automatically verify (say test) that those examples actually work. Haddock 'head' has some very new and immature support for 'examples', and I'm working on integrating it with my DocTest package. Besides that, a way to write larger tutorials (that we can test) would also be nice.
I'm more than open to better suggestions. I'll also appreciate any help in improving my documentation.
I'm working on a (very) short introduction to WAI, not sure when I'll have time to finish it. Cheers, Simon