We, at Castle, are occasionally getting bashed at the lack of documentation. I think that the area most users are complaining about is Windsor and MonoRail, (as these two are evolving in the most rapid way).
My personal view on the matter is that since the whole Castle stack, and especially MonoRail and Windsor, are all about “zero friction” and “Convention over Configuration”, the easiest way is to lay hands on sample or oss code and apply that you your solution.
Anyway, in the Alt.NET uk thing that was at Conchango/London last month I’ve met one Symon Rottem. It appear that this guy know his way around tech-docs, and he had picked up that errand, and started putting effort in improving the overall documentation level for Castle, especially the User-Manual part (as the API actually is being generated and is quite good).
I’d also recommend his (young yet promising) blog. It’s on my Google-reader blogroll for quite some time, and I really need to add “Import OPML” to my blog so I’d be able to update the blogs list on the side panel here.