Multigrid tutorial/book

I was reading Press et. al., "Numerical Recipes" book, which contain section about multigrid method for numerically solving boundary value problems.

However, the chapter is quite brief and I would like to understand multigrids to a point where I will be able to implement more advanced and faster version than that provided in the book.

The tutorials I found so far are very elaborate and aimed on graduate students. I have notions on several related topics (relaxation methods, preconditioning), but still the combination of PDEs and the multigrid methods is mind-blowing for me...

Thanks for any tips for a good explanatory book, website or article.

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What equation you are trying to solve, there are many newly developed fast multigrid methods like AMG, local multigrid, etc. –  Shuhao Cao Sep 20 '12 at 3:44
@ShuhaoCao I am especially interested in linear elliptic (Poisson) equation, but I would like to understand how to use multigrid with other PDEs (e.g. diffusion equation). I am also interested in other relaxation methods than Gauss-Seidel, still usable with multigrid (e.g. Conjugate Gradient). –  Libor Sep 20 '12 at 10:45

IMHO Vassilevski from Lawrence Livermore national laboratory puts up a series of very beginner-oriented lecture notes, where he introduced the motivation and preliminary first, how to get the $Ax = b$ type linear equation system from a boundary value problem of $-\Delta u = f$ with $u = g$ on $\partial \Omega$, what is condition number and how does it affect our iterative solvers.