Some time ago I wrote an article (in Dutch) about Sandcastle and some of the available third-party tools. About one month ago, it was published in the Dutch .Net magazine. Kind of proud now it's in print. I didn't post about it before, because the article wasn't available on the internet yet. It is now and the PDF of the article can be found here:
http://download.microsoft.com/download/0/3/2/0329df9d-70df-44fc-b421-a32bf5fab2c3/dnm20_p71-74_1.19.pdf
All other articles, and older publications of the magazine can be found here:
http://www.microsoft.com/netherlands/msdn/netmagazine/code/magazine20.aspx
It's in Dutch I'm afraid.