There are many tutorials on the web for D9P (Disappearing 9 patch). Here is one that I just recently came across that has good pics and simple instructions.
http://www.popularpatchwork.com/news/article.asp?a=5294
One of the many things I like about this pattern is the variety with which you can sew the 9 patches back together. One of the ladies in my quilt class made several scrappy 9 patches, cut them up like the pattern says, but then she mixed all the cut pieces up from all the 9 patches, and sewed them back together randomly. It looked REALLY scrappy!!