Books on Tarot Spreads
Teresa Michelsen has a great book on designing your own Tarot spreads called, logically enough, Designing Your Own Tarot Spreads. It's from Llewellyn.
For a quick gallery of hundreds of spreads, it's hard to beat the oddly-named Power Tarot by Trish Macgregor and Phyllis Vega.
Hope this helps!
Mark