Thanks to everyone who has visited and taken an interest in my marbling project. It's amazing what one's waking thoughts can spawn. :-)
So many people have said they'd like to give it a go that I thought I'd put a couple of links here to give a head start. I'm sure there will be more, and some will be better or different so I wouldn't say these are the whole story. Hope it's helpful, and please add to the resources if you find something wonderful.
The first is Princeton On-line which is a teaching resource.
The second is from Spotlight which is a large chain of haberdashery shops in Australia.
Happy marbling and enjoy the puddling.