If any of you are looking for a good reference on how to generate structured quad or hex grids (otherwise known as mapped meshes) the first place you should look is the classic text Numerical Grid Generation by Thompson, Warsi, and Mastin.
Chapters include boundary-conforming coordinate systems, transformation relations, numerical implementation, truncation error, elliptic generation systems, parabolic and hyperbolic generation systems, algebraic generation systems, orthogonal systems, conformal mapping, and adaptive grids.
Plus, the entire text is available online for free at Mississippi State University including downloadable PDFs. Check it out today at www.erc.msstate.edu/publications/gridbook/.
This question comes up often enough on the CFD Online Forums that I thought it would be a good idea to post the answer here too.
Maybe someday John Steinbrenner and I will compile our notes from the graduate course we taught on mesh generation and make our own book. But in the meantime, your first reference for structured grids should be Thompson, Warsi, and Mastin’s book.