I've added them all to the cover gallery on the website. Here are some of my favorites:

The Gabriel Hounds, original UK hardback, Hodder & Stoughton, 1967. I love the colors on this one.
Touch Not the Cat, UK hardback, Hodder & Stoughton, 1976
Thunder on the Right, US Fawcett paperback. I like this one, but why on earth is Jennifer Silver wearing a medieval costume??