I have read a lot about Gann's methods and have dabbled with a few of them. I think if you are prepared to do some work, there are some methods that might be of use. There is a lot of information in yahoo groups and I wouldn't pay for anything, as a lot of the books probably have less information than can be found for free.
This chart is of the daily S&P from the high in 2000on a squared chart I made in excel. I like to keep an eye on the 45° lines.