Look at this video. Possibly the best I've ever seen.
Watch this one first.
http://www.youtube.com/watch?v=1juxfPwy2tg&mode=user&search=
Than this one.
http://www.youtube.com/watch?v=VVYcmsFYQCs&mode=related&search=
Cool huh? :o
I saw a neat little plan for something like this in '48 top notch track plans'