Book for algorithms beyond Cormen I've finished most of the material in Cormen's Intro to Algorithms book and I am looking for an algorithms book that covers material beyond Corman's book. Are there any recommendations?

NOTE: I asked this on stackoverflow but wasn't all too happy with the answer. 

NOTE: Looking at most of the comments I think ideally I would like to find a book that would cover the material of the the 787 course in this course description.
As others have noted, books about (advanced) algorithms are best selected by topic. A good but heavy-weight general reference with rigorous analysis is probably The Art of Computer Programming by Knuth.

As for analysis techniques, you may be interested in An Introduction to the Analysis of Algorithms by Sedgewick and Flajolet, and Algorithmic Combinatorics by Flajolet and Sedgewick for more theory in the same direction.

For approaches on tackling hard problems, see Algorithmics for Hard Problems by Hromkovič.