'The Algorithm Design Manual' by Steven Skiena at Stony Brook is a very pragamatic book for intermediate data structures and algorithms. This is a definitely aimed at the practitioner who must get something up and running, without having to worry about big-Oh notation etc. There's an online version of the book but it's just so good, I'd recommend that anyone who needs this information, snap up a copy. Skiena also maintains The Stony Brook Algorithm Repository It's a treasure, as it includes implementations of some of these algorithms in a variety of programming languages. The web page does look somewhat dated, but as a good first step into intermediate data structures and algorithms.