Re: blue-eyed parents having a brown-eyed child... apparently it's all to do with the phenotypes being either recessive or dominant. I checked out this page:
http://www.madsci.org/posts/archives/jun2000/96169
6074.Ge.r.html
Hope it helps!
Re: white parents having a black child... I seem to remember reading an article a few years ago about a black child being born to white parents. The reason given for this was that the mother's great, great grandmother was black, and the new baby had inherited enough of his/her predecessor's genes to be 'darker' than it's parents. As this was a few years ago, I can't be more specific than that, sorry.